LHC Physics Alan Barr UCL. This morning’s stuff… Higgs – why we expect it, how to look for it,...
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Transcript of LHC Physics Alan Barr UCL. This morning’s stuff… Higgs – why we expect it, how to look for it,...
LHC Physics
Alan Barr UCL
This morningrsquos stuffhellip
Higgs ndash why we expect it how to look for it hellip
Supersymmetry ndash similar questions
Smorgasbord of other LHC physics
Physics at TeV-scale
bull Dominated by the physics ofElectroweak Symmetry Breaking
bull Answering the question ndash ldquoWhy do the W and Z bosons have massrdquo
bull Standard Model suggests Higgs mechanismndash However Higgs boson predicted by SM not
yet observed
Higgs mechanism - historybull 1964 Demonstration that a scalar field with
appropriate interactions can give mass to gauge bosonsndash Peter Higgs (Edinburgh previously UCL) ndash Independently discovered by Francois Englert and
Robert Brout (Brussels)
bull Not until 1979 that Salam Weinberg and Glashow use this in a theory of electroweak symmetry breaking ndash For a biographic article on P Higgs see
httpphysicsweborgarticlesworld1776
Higgs mechanism why needed
bull Example of P Higgs ndash give mass to a U(1) boson (heavy ldquophotonrdquo in a QED-like theory)
Start with QED Lagrangian
Which is invariant under the local U(1) gauge transformation
But this isnrsquot invariant under gauge transformation () so is not allowed
Adding a gauge boson mass term could be attempted with a term like
where
()
Instead add a complex scalar field which couples to the gauge boson Instead add a complex scalar field which couples to the gauge boson
Pictorial representation
Scalar field strength = 0
Degenerate minimumVacuum (field strengthne0)
Quartic term self-couplingpositive
Quadratic coupling termnegative
Excitations in this direction produce physical Higgs boson
Excitations in this direction produce physical Higgs boson
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
If you donrsquot understand this study PhysLett12132-1331964
Higgs field ldquoeats Goldstone bosonrdquo
bull Flat direction in potential usually represents zero-mass particlendash ldquoGoldstone bosonrdquo
bull But in Higgs theory this direction is coupled to the gauge bosonndash No massless Goldstone bosonndash Instead mass term generated for
gauge boson
φφ
Gauge boson
Example of a Feynmandiagram showing a contribution to the gaugeboson mass term
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
φ
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
This morningrsquos stuffhellip
Higgs ndash why we expect it how to look for it hellip
Supersymmetry ndash similar questions
Smorgasbord of other LHC physics
Physics at TeV-scale
bull Dominated by the physics ofElectroweak Symmetry Breaking
bull Answering the question ndash ldquoWhy do the W and Z bosons have massrdquo
bull Standard Model suggests Higgs mechanismndash However Higgs boson predicted by SM not
yet observed
Higgs mechanism - historybull 1964 Demonstration that a scalar field with
appropriate interactions can give mass to gauge bosonsndash Peter Higgs (Edinburgh previously UCL) ndash Independently discovered by Francois Englert and
Robert Brout (Brussels)
bull Not until 1979 that Salam Weinberg and Glashow use this in a theory of electroweak symmetry breaking ndash For a biographic article on P Higgs see
httpphysicsweborgarticlesworld1776
Higgs mechanism why needed
bull Example of P Higgs ndash give mass to a U(1) boson (heavy ldquophotonrdquo in a QED-like theory)
Start with QED Lagrangian
Which is invariant under the local U(1) gauge transformation
But this isnrsquot invariant under gauge transformation () so is not allowed
Adding a gauge boson mass term could be attempted with a term like
where
()
Instead add a complex scalar field which couples to the gauge boson Instead add a complex scalar field which couples to the gauge boson
Pictorial representation
Scalar field strength = 0
Degenerate minimumVacuum (field strengthne0)
Quartic term self-couplingpositive
Quadratic coupling termnegative
Excitations in this direction produce physical Higgs boson
Excitations in this direction produce physical Higgs boson
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
If you donrsquot understand this study PhysLett12132-1331964
Higgs field ldquoeats Goldstone bosonrdquo
bull Flat direction in potential usually represents zero-mass particlendash ldquoGoldstone bosonrdquo
bull But in Higgs theory this direction is coupled to the gauge bosonndash No massless Goldstone bosonndash Instead mass term generated for
gauge boson
φφ
Gauge boson
Example of a Feynmandiagram showing a contribution to the gaugeboson mass term
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
φ
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Physics at TeV-scale
bull Dominated by the physics ofElectroweak Symmetry Breaking
bull Answering the question ndash ldquoWhy do the W and Z bosons have massrdquo
bull Standard Model suggests Higgs mechanismndash However Higgs boson predicted by SM not
yet observed
Higgs mechanism - historybull 1964 Demonstration that a scalar field with
appropriate interactions can give mass to gauge bosonsndash Peter Higgs (Edinburgh previously UCL) ndash Independently discovered by Francois Englert and
Robert Brout (Brussels)
bull Not until 1979 that Salam Weinberg and Glashow use this in a theory of electroweak symmetry breaking ndash For a biographic article on P Higgs see
httpphysicsweborgarticlesworld1776
Higgs mechanism why needed
bull Example of P Higgs ndash give mass to a U(1) boson (heavy ldquophotonrdquo in a QED-like theory)
Start with QED Lagrangian
Which is invariant under the local U(1) gauge transformation
But this isnrsquot invariant under gauge transformation () so is not allowed
Adding a gauge boson mass term could be attempted with a term like
where
()
Instead add a complex scalar field which couples to the gauge boson Instead add a complex scalar field which couples to the gauge boson
Pictorial representation
Scalar field strength = 0
Degenerate minimumVacuum (field strengthne0)
Quartic term self-couplingpositive
Quadratic coupling termnegative
Excitations in this direction produce physical Higgs boson
Excitations in this direction produce physical Higgs boson
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
If you donrsquot understand this study PhysLett12132-1331964
Higgs field ldquoeats Goldstone bosonrdquo
bull Flat direction in potential usually represents zero-mass particlendash ldquoGoldstone bosonrdquo
bull But in Higgs theory this direction is coupled to the gauge bosonndash No massless Goldstone bosonndash Instead mass term generated for
gauge boson
φφ
Gauge boson
Example of a Feynmandiagram showing a contribution to the gaugeboson mass term
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
φ
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Higgs mechanism - historybull 1964 Demonstration that a scalar field with
appropriate interactions can give mass to gauge bosonsndash Peter Higgs (Edinburgh previously UCL) ndash Independently discovered by Francois Englert and
Robert Brout (Brussels)
bull Not until 1979 that Salam Weinberg and Glashow use this in a theory of electroweak symmetry breaking ndash For a biographic article on P Higgs see
httpphysicsweborgarticlesworld1776
Higgs mechanism why needed
bull Example of P Higgs ndash give mass to a U(1) boson (heavy ldquophotonrdquo in a QED-like theory)
Start with QED Lagrangian
Which is invariant under the local U(1) gauge transformation
But this isnrsquot invariant under gauge transformation () so is not allowed
Adding a gauge boson mass term could be attempted with a term like
where
()
Instead add a complex scalar field which couples to the gauge boson Instead add a complex scalar field which couples to the gauge boson
Pictorial representation
Scalar field strength = 0
Degenerate minimumVacuum (field strengthne0)
Quartic term self-couplingpositive
Quadratic coupling termnegative
Excitations in this direction produce physical Higgs boson
Excitations in this direction produce physical Higgs boson
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
If you donrsquot understand this study PhysLett12132-1331964
Higgs field ldquoeats Goldstone bosonrdquo
bull Flat direction in potential usually represents zero-mass particlendash ldquoGoldstone bosonrdquo
bull But in Higgs theory this direction is coupled to the gauge bosonndash No massless Goldstone bosonndash Instead mass term generated for
gauge boson
φφ
Gauge boson
Example of a Feynmandiagram showing a contribution to the gaugeboson mass term
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
φ
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Higgs mechanism why needed
bull Example of P Higgs ndash give mass to a U(1) boson (heavy ldquophotonrdquo in a QED-like theory)
Start with QED Lagrangian
Which is invariant under the local U(1) gauge transformation
But this isnrsquot invariant under gauge transformation () so is not allowed
Adding a gauge boson mass term could be attempted with a term like
where
()
Instead add a complex scalar field which couples to the gauge boson Instead add a complex scalar field which couples to the gauge boson
Pictorial representation
Scalar field strength = 0
Degenerate minimumVacuum (field strengthne0)
Quartic term self-couplingpositive
Quadratic coupling termnegative
Excitations in this direction produce physical Higgs boson
Excitations in this direction produce physical Higgs boson
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
If you donrsquot understand this study PhysLett12132-1331964
Higgs field ldquoeats Goldstone bosonrdquo
bull Flat direction in potential usually represents zero-mass particlendash ldquoGoldstone bosonrdquo
bull But in Higgs theory this direction is coupled to the gauge bosonndash No massless Goldstone bosonndash Instead mass term generated for
gauge boson
φφ
Gauge boson
Example of a Feynmandiagram showing a contribution to the gaugeboson mass term
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
φ
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Pictorial representation
Scalar field strength = 0
Degenerate minimumVacuum (field strengthne0)
Quartic term self-couplingpositive
Quadratic coupling termnegative
Excitations in this direction produce physical Higgs boson
Excitations in this direction produce physical Higgs boson
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
Excitations in this direction = gauge transformation- Global transformationsunobserved- Local transformations give mass to gauge bosons
If you donrsquot understand this study PhysLett12132-1331964
Higgs field ldquoeats Goldstone bosonrdquo
bull Flat direction in potential usually represents zero-mass particlendash ldquoGoldstone bosonrdquo
bull But in Higgs theory this direction is coupled to the gauge bosonndash No massless Goldstone bosonndash Instead mass term generated for
gauge boson
φφ
Gauge boson
Example of a Feynmandiagram showing a contribution to the gaugeboson mass term
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
φ
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Higgs field ldquoeats Goldstone bosonrdquo
bull Flat direction in potential usually represents zero-mass particlendash ldquoGoldstone bosonrdquo
bull But in Higgs theory this direction is coupled to the gauge bosonndash No massless Goldstone bosonndash Instead mass term generated for
gauge boson
φφ
Gauge boson
Example of a Feynmandiagram showing a contribution to the gaugeboson mass term
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
NB Our example here was for a single complex scalar and for a U(1) fieldIn the Standard Model the Higgs is an electroweak SU(2) doublet field with 4 degrees of freedom 3 of these are lsquoeatenrsquo by Wplusmn Z0 mass terms leaving a single scalar for the physical Higgs boson
For full SU(2) treatment see eg Halzen amp Martin section 149
φ
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Constraints on the Higgs mass
bull Higgs boson mass is the remaining unpredicted parameter in Standard Model
bull Higgs self-couplings not predictedbull So Higgs mass not predicted by Electroweak theory
bull However there are1 Bounds from theory
bull Perterbative unitarity of boson-boson scattering
2 Indirect boundsbull Loop effects on gauge boson masses
3 Direct boundsbull Searches
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
PhysRevD1615191977 Without other new physics the Higgs boson must exist amp have mass lt 1 TeV
Vector Boson scattering
Perturbative limit
Halzen amp Martin section 156
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Indirect Higgs bounds LEP Electroweak data
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
bull W (and Z) mass depends on mHiggsndash Logarithmic loop corrections to
massesndash Also depends on top mass
httplepewwgwebcernchLEPEWWG
Measurements
Prediction as a function of mH
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Direct boundsHiggs searches LEP
bull No discoverybull Direct lower bound at 1144 GeV
PhysLett B565 (2003) 61-75
Higgsstrahlung ndash dominant production
ALEPHCandidate vertex
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Higgs-Hunter Situation Report
bull Something very much like the Higgs must exist with ~100 GeV lt m lt ~1 TeV
bull No discovery as yetbull If it is a Standard Model Higgs the constraints are
tighter 1144 GeV lt mSM Higgs lt 199 GeV
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
The Large Hadron Collider
bull Largendash 27 km circumferencendash Built in LEP tunnel
bull Hadron ndash Mostly protonsndash Can also collide ions
bull Colliderndash ~ 7 x higher collision
energyndash ~ 100 x increase in
luminosityndash Compared to Tevatron
Proton on Protonat radics = 14 TeV
Design luminsoity ~~100 fb-1 expt year
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
General Purpose Detectors
ATLAS
Similarities1 Tracker2 Calorimeter3 Muon chambers
DifferencesSize CMS ldquocompactrdquoMagnetic-field configurationATLAS has muon toroidsElectromagnetic-CalorimeterCMS crystals ATLAS Liquid ArgonOuter tracker technologyCMS all-silicon ATLAS straw tubes
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Definitions
z
z
pE
pEy
log21
BarrelldquoCentralrdquo
EndcapldquoForwardrdquo
EndcapldquoForwardrdquo
Beam pipe
proton proton
x
y
φ
θ
Particle
Rapidity
Pseudorapidity )]2ln[tan(
Differences in rapidity are conservedunder Lorentz boosts in the z-direction
Good approximation to rapidity if Egtgtm
η = 0η = -1
z
ldquoTransverserdquo pT = (px py) |pT| = radic(px2 py
2)
η = -2
η = -3
η = +1
η = +2
η = +3
prove these
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Making particles in hadron colliders
bull Hadron-Hadron collisions complicatedndash See lectures by Mark Lancaster
(ldquoHadron Collider Physicsrdquo)ndash QCD Lots of background events with jetsndash QCD Lots of hadronic ldquorubbishrdquo in signal events ndash Hard scatters are largely from q-qbar or glue-glue
bull Proton structure is important ndash See lectures by Robert Thorne
bull But they provide the highest energies availablebull Often these are the discovery machines
proton proton
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
LHCb
bull Asymmetric detector for B-meson physics
For more information see Lazzeroni talk athttpindicocernchconferenceDisplaypyconfId=5426
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
LHCb Physics
bull VCKM must be unitary VVdagger = V daggerV = 1
bull Multiply out rows amp columns
Quark flavour e-states are not the same as mass e-states mixing
Do thisDo this
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
LHCb Physics
bull Measurements of decay rates and kinematics tell us about squark mixings
bull Over-constraining triangles gives sensitivity to new physics through loop effects
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
bull Signals for QGPndash Jet quenching
ndash Quarkonim (eg Jψ) suppression (ldquomelt bound statesrdquo)
ALICEbull Designed to examine
collisions of heavy ions (eg lead-lead or gold-gold)
bull Theorised to produce a new state of matter ndash a quark-gluon plasma
bull Quarks no longer confined inside colourless baryons
QGP JetNo Jet
Jψ c
c
_
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Couplings of the SM Higgs
bull Couplings proportional to mass
bull What does this mean for the Higgs-hunter
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Producing a Higgs
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash u-ubar H
has very small cross-section
ndash Dominant production via vertices coupling Higgs to heavy quarks or WZ bosons
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Production cross-sections
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Decay of the SM Higgs
bull Width becomes large as WW mode opensbull Branching ratios change rapidly as new
channels become kinematically accessible
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Needle in a haystackhellip
Higgs production
QCD jet productionat high energy
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Need to use signatures with small backgrounds- Leptons- High-mass resonances- Heavy quarksto avoid being overwhelmed
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Example 1 H ZZ
bull Only works when mHiggs gt~ 2MZ
bull When the Z decays to leptons there are small backgrounds
q
q_ H
Z
Z
e+
e-
e+
e-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
H ZZ
H ZZ e+e- e+e-H ZZ e+e- e+e-
CMS
Electrons have track (green ) amp energy deposit (pink)
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
H ZZ e+e- e+e-
Plot shows simulated distributions of [invariant mass of four electrons] for 3 different values of mHiggs(We wouldnrsquot see all of these together)
q
q_ H
Z
Z
e+
e-
e+
e-
1 Find events consistent with above topology(four electrons)
2 Add together the fourelectron 4-vectors
3 Find the mass of the resultant4-vector ( mass of the Higgs)
mH=130mH=170
mH=150
background
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Example (2) H γγbull No direct coupling
of H to photonbull However allowed at
loop levelbull Branching ratio
~ 10 -3
(at low mHiggs)bull Important at low
massbull Actually a very
clean way of looking for Higgsndash Small backgrounds
Production and decay of Higgsthrough lsquoforbiddenrsquo direct couplings
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
H γγ CMS simulation Physics TDR 2006H γγ CMS simulation Physics TDR 2006
γ
γ
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
H γγ
bull Simulation by CMS for different Higgs massesfor early LHC data (1 fb-1)
Higgs signalscaled up by factor 10
Invariant mass of the pair of photons
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
H γγ hellip backgrounds
ldquoIrreduciblerdquo2 real photons
ldquoReduciblerdquoeg fake photons
γ
gluon
q
q_
π0
γγ
Need v good calorimetersegmentationto separate these
ldquoBornrdquo ldquoBoxrdquo
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Significance
H-gtZZ
Significance is a measureof the answer to the questionldquoWhat is the probabilitythat a backgroundfluctuation would producewhat I am seeingrdquo
5- means ldquoprobabilitythat background fluctuation does this is less than 28510-7 rdquo
5- is usually takenas benchmarkfor ldquodiscoveryrdquo
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
After discovery of Higgs
bull Measure Higgs massndash The remaining unconstrained parameter of the Standard Model
bull Measure Higgs couplings to fermions and vector bosonsndash All predicted by Standard Modelndash Check Higgs mechanism
bull Couplings very important since there may be more than one Higgs bosonndash Theories beyond the Standard Model (such as Supersymmetry)
predict multiple Higgs bosonsndash In such models the couplings would be modified
bull Do direct searches for further Higgs bosons
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
If no Higgs found
bull Arguably more exciting than finding Higgsbull Look at WW scattering process
ndash Look for whatever is ldquofixingrdquo the cross-sectionndash Eg exotic resonances
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
What is supersymmetry
bull Nature permits only particular types of symmetryndash Space amp time
bull Lorentz transformsbull Rotations and translations
ndash Gauge symmetrybull Such as Standard Model
force symmetriesbull SU(3)c x SU(2)L x U(1)
ndash Supersymmetrybull Anti-commuting
(Fermionic) generators bull Changes Fermions into
Bosons and vice-versa
bull Consequencesndash Supersymmetric theory has
a Boson for every Fermion and vice-versa
bull Doubles the particle contentndash Partners to Standard Model
particles not yet observed
Examples of Supersymmetric partner-states
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Extended higgs sector 2 cplx doublets 8-3 = 5 Higgs bosons
(S)ParticlesStandard
ModelSupersymmetric
partners
quarks (LampR)leptons (LampR) neutrinos (Lamp)
squarks (LampR)sleptons (LampR)sneutrinos (Lamp)
Z0
Wplusmn
gluon
BW0
h0
H0
A0
Hplusmn
H0
Hplusmn
4 x neutralino
2 x chargino
AfterMixing
gluino
Spin-12
Spin-1
Spin-0
Spin-12
Spin-0
BinoWino0
Winoplusmn
gluino
~
~
(Higgsinos)
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Why Supersymmetrybull Higgs mass
ndash Quantum corrections to mH
ndash Would make ldquonaturalrdquo mass near cut-off (Unification or Planck scale)
ndash But we know mH lt~ 1 TeVndash mH = mH bare + mH
ndash Severe fine tuning required between two very big numbers
bull Enter Supersymmetry (SUSY)ndash Scalar partner of quarks also
provide quantum correctionsndash Factor of -1 from Feynman rulesndash Same coupling λndash Quadratic corrections cancelndash mH now natrually at electroweak
scale
top
Δm2(h) Λ2cutoff
higgs higgs
λλ
stop
higgs higgs
λ λ
Quantum correction to mHiggs
Cancelling correction to mHiggs
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Further advantagesbull Lightest SUSY
particle isndash Lightndash Weakly interacting ndash Stablendash Massive
bull Good dark matter candidate
bull Predicts gauge unificationndash Extra particles modify
running of couplingsndash Step towards ldquohigher
thingsrdquo
SM
+SUSY
Log10 (μ GeV)
Log10 (μ GeV)
miss
Hit
1α 1α
Big Bang relic abundance calculations are in good agreement with WMAP microwave background observations in regions of SUSY parameter space
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
R-paritybull Multiplicative discrete quantum
numberbull RP = (-1)2s+3B+L
ndash S=spin B=baryon number L=lepton number
bull Standard Model particles have RP = +1
bull SUSY Model particles have RP = -1
bull If RP is conserved then SUSY particles must be pair-produced
bull If RP is conserved then the Lightest Supersymmetric Particle (LSP) is stable
Example of a Feynmandiagram for proton decaywhich is allowed if the RP-violating couplings (λ) are not zero
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
How is SUSY brokenbull Direct breaking in
visible sector not possiblendash Would require
squarkssleptons with mass lt mSM
ndash Not observedbull Must be strongly
broken ldquoelsewhererdquo and then mediatedndash Soft breaking terms
enter in visible sectorndash (gt100 parameters)
Stronglybrokensector
Weakcoupling(mediation)
Soft SUSY-breaking termsenter lagrangianin visible sector
Various models offer different mediation egGauge ldquoGMSBrdquoGravity ldquomSUGRArdquo (supergravity)
Anomaly ldquoAMSBrdquo
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Sparticle Interactions
bull Interactions amp couplings same as SM partners
bull 2 SUSY legs for RP conservation
Largely partnerof W0 boson
Largely partnerof W0 boson
Q Does the gluino couple tothe quarkthe sleptonthe photino
Q Does the gluino couple tothe quarkthe sleptonthe photino
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
General featuresMassGeV
ldquotypicalrdquo susy spectrum(mSUGRA)
bull Complicated cascade decaysndash Many
intermediates
bull Typical signalndash Jets
bull Squarks and Gluinos
ndash Leptonsbull Sleptons and weak
gauginos
ndash Missing energybull Undetected
Lightest Susy Particle
Production dominatedby squarks and gluinos
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
The ldquoreal thingrdquo(a simulation ofhellip)
bull Two high-energy jets of particlesndash Visible decay
productsbull ldquoMissingrdquo
momentumndash From two
invisible particles
ndash these are the invisible Dark Matter guys
Proton beams perpendicular to screenProton beams perpendicular to screen
Invisibleparticles
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Standard Model backgrounds measure from LHC DATA
bull Example backgroundto ldquo4 jets + missing energyrdquondash Measure background in control regionndash Extrapolate to signal regionndash Look for excess in signal region
Measure in Z -gt μμ
Use in Z -gt νν R Z
B Estimated
R Z
B Estimated
μ μ
With SUSY
Missing PT GeV
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Constraining SUSY massesbull Mass constraintsbull Invariant masses in pairs
ndash Missing energyndash Kinematic edges
Observable Depends on
Limits depend on angles betweensparticle decays
Frequently-studieddecay chain
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Mass determination
Measureedges
Variety of edgesvariables
Try variousmasses in equations
CG Lester
bull Narrow bands in ΔMbull Wider in mass scalebull Improve using cross- section information
These measurements can tell us about SUSY breaking
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Other things to do with SUSY
bull Measure the sparticle spins ndash ldquoproverdquo that it is really supersymmetric
partners we are seeing
bull Measuring the couplings amp mixingsndash Use to ldquopredictrdquo Dark Matter relic density
bull Find the extra Higgs bosonsndash Recall that SUSY predicts 5 Higgs bosonsndash Now we want to find H0 h0 A0 Hplusmn
ndash Also measure their couplings CP hellip
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Standard Model Physics
bull The ATLAS and CMS experiments also potentially can measurendash Top massndash W massndash Rare B-meson decay ratesndash Jet physics
bull To much higher precision that is currently achievablendash Large number of eg top quarks
producedndash Small statistical errorsndash Systematic errors (such as jet
energy scale determination) limiting
Mass of hadronic top
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Other things to look forhellip
bull Leptoquarksndash Motivated by Grand Unified Theoriesndash Carry lepton and baryon numberndash Eg LQ bμ
bull New heavy quarksndash Predicted by some non-SM Higgs theories
bull New heavy gauge bosonsndash Indications of new symmetry groups
bull Extra dimensionsndash Large variety of models on the market
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Extra dimensions models
bull Motivated by need for ED in string theory and m-theoryndash Logical a possibility for a LHC discovery
bull Different modelshellipndash Which particles are localised where (bulkbrane)ndash Form of space-time metric (flatwarped)ndash Geometry and size of extra dimensions
bull hellipmake different predictionsndash Kalazua-Klein resonances of SM particlesndash Graviton statesndash Stringy resonancesndash Effects of strong gravity (micro Black Holes)ndash Energy loss into extra dimensions
More informationhttpeps2003physikrwth-aachendedatatalksparallel09StringTheory09Vacavantppt
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
General sources
bull Higgs at the LHC talk by Zeppenfeld httpwhepp9iopbresintalkszeppenfeld_WHEPP9pdf
bull Physics at the LHC Higgs talk by HarlanderhttpnewtonftjagheduplphysLHC
bull ATLAS physics Technical Design Report (TDR)httpatlaswebcernchAtlasGROUPSPHYSICSTDRaccesshtml (1999)
bull CMS physics Technical Design Report (TDR)httpcmsdoccernchcmscpttdr (2006)
bull Supersymmetry httparxivorgabshep-ph9709356
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Constraints on mHiggs
Scale at which new physics enters
Unstable vacuum
No perturbative unitarity
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Producing a Higgs LHC
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
bull Higgs couplings massndash Direct eg u-ubar H
very small cross-sectionbull Dominant production via
vertices coupling Higgs to heavy quarks or WZ bosons
top
H
g
g
WZH
q
q_
top
H
g
gWZ
H
q
q_
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Higgsrsquo mechanismbull Add a complex scalar field
ndash In fact he adds 2 real scalar fields
(fermion part of L now ignored)
This is gauge invariant when the scalars have covariant derivatives
Now if the potential V has a degenerate minimum at φne0 we get interesting consequenceshellip
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
NB scalar field must couple to gauge field likethis for the Higgsmechanism to work
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
mSUGRA ndash ldquosuper gravityrdquobull AKA cMSSMbull Gravity mediated SUSY
breakingndash Flavour-blind (no FCNCs)
bull Strong expt limitsndash Unification at high scales
bull Reduce SUSY parameter spacendash Common scalar mass M0
bull squarks sleptonsndash Common fermionic mass Mfrac12
bull Gauginosndash Common trilinear couplings A0
bull Susy equivalent of Yukawas
Programs includeeg ISASUSYSOFTSUSY
1016 GeV
EW scale
Iterate usingRenormalisationGroupEquations
Unification of couplings
Correct MZ MW hellip
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Other suggestions for SUSY breaking
bull Gauge mediationndash Gauge (SM) fields in extra dimensions mediate SUSY breaking
bull Automatic diagonal couplings no EWSB
ndash No direct gravitino mass until Mpl
bull Lightest SUSY particle is gravitinobull Next-to-lightest can be long-lived (eg stau or neutralino)
bull Anomaly mediationndash Sequestered sector (via extra dimension)
bull Loop diagram in scalar part of graviton mediates SUSY breakingbull Dominates in absence of direct couplings
ndash Leads to SUSY breaking RGE β-functionsbull Neutral Wino LSPbull Charged Wino near-degenerate with LSP lifetime bull Interesting track signatures
Not exhaustive
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
Producing exotics
Time
standard
exotic
Time
standard
exotic
Time
standard
exotics
Time
standardexotics
bull If exotics can be produced singly they can decayndash No good for
Dark Matter candidate
bull If they can only be pair-produced they are stablendash Only
disappear on collision (rare)
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
Require an even number of exotic legs tofrom blobs(Conserved multiplicative quantum number)
If we want a good dark matter candidate
No RP
With RP
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-
How do they then behave
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
bull Events build from blobs with 2 ldquoexotic legsrdquo
bull A pair of cascade decays results
bull Complicated end result
Time
standard
2 exotics
Production part
Time
standard
heavyexotic lighter
exotic
Decay part Time
Complete ldquoeventrdquo
= exotic= standard
- LHC Physics
- This morningrsquos stuffhellip
- Physics at TeV-scale
- Higgs mechanism - history
- Higgs mechanism why needed
- Pictorial representation
- Higgs field ldquoeats Goldstone bosonrdquo
- Constraints on the Higgs mass
- Perturbative limit
- Indirect Higgs bounds LEP Electroweak data
- Direct bounds Higgs searches LEP
- Higgs-Hunter Situation Report
- Slide 13
- The Large Hadron Collider
- General Purpose Detectors
- Definitions
- Making particles in hadron colliders
- LHCb
- LHCb Physics
- Slide 20
- ALICE
- Slide 22
- Couplings of the SM Higgs
- Producing a Higgs
- Production cross-sections
- Decay of the SM Higgs
- Slide 27
- Example 1 H ZZ
- H ZZ
- H ZZ e+e- e+e-
- Example (2) H γγ
- Slide 32
- H γγ
- H γγ hellip backgrounds
- Significance
- After discovery of Higgs
- If no Higgs found
- Slide 39
- What is supersymmetry
- (S)Particles
- Why Supersymmetry
- Further advantages
- R-parity
- How is SUSY broken
- Sparticle Interactions
- Slide 47
- General features
- The ldquoreal thingrdquo (a simulation ofhellip)
- Standard Model backgrounds measure from LHC DATA
- Constraining SUSY masses
- Mass determination
- Other things to do with SUSY
- Standard Model Physics
- Other things to look forhellip
- Extra dimensions models
- Slide 57
- General sources
- Constraints on mHiggs
- Producing a Higgs LHC
- Higgsrsquo mechanism
- mSUGRA ndash ldquosuper gravityrdquo
- Other suggestions for SUSY breaking
- Producing exotics
- How do they then behave
-