Millennial Physics at Fermilab - Michigan State University · Chip Brock, Michigan State University...

Chip Brock, Michigan State University

physics at fermilab

April 1, 1999 Fermilab at the Millennium

The high energy physics program at theNation’s Premier platform for

DISCOVERY

Millennial Physics atFermilab

• Introduction• Standard Model• Fermilab and detectors• Remembrance of Things Past

emphasis on top• The future

Raymond BrockDepartment of Physics and Astronomy

Michigan State [email protected]


physics at fermilab


what is it?

Fermilab is many things…

First, a dedicated scientific community

made up of:

– 1200 physicists, engineers, and staff

– 1000 faculty, post docs, and students from > 80 US &20 foreign institutions

plus a wonderful scientific instrument

consisting of:

– a time machine

– A particle accelerator for antirotating beams of protonsand antiprotons

– hand-made vehicles to explore the current and the veryearly universe

– A source of high energy/intensity beams of kaons andneutrinos

Officially, a single-purpose DOE national lab

located at:

– real space: 60 mi west of Chicago– cyberspace: www.fnal.gov


physics at fermilab


Standard Model–what we know

Quarks (spin 1/2, charge 2/3 and -1/3)

Leptons (spin 1/2, charge 1 and 0)

Gauge bosons (spin 1, charge 1 and 0)

Higgs (spin 0, charge 0)

ud

cs

tb

left-handed:

right-handed: u, d, c, s, t, b

weak, strong, andelectromagnetic interactions

electromagnetic and stronginteractions

eνe

µνµ

τντ

left-handed:

right-handed: e, µ, τ

weak and electromagneticinteractions

electromagnetic interactions

g,γ,

W±,Z 0

strong,

H 0Fills the vacuum and isresponsible for mass?

electromagnetic

electromagnetic & weak

electromagnetic & weak


physics at fermilab


B+

B-

B0

A0

complex, spin 0

doublets

The phase transition...

H0

You are here...

γ

Z0

1015 K10-12 sec

1 K10+18 sec

θW = 28º

W±

TC

A useful way to think about things: think back…way back

Count the dof: massless, spin 1 = 2massive spin 1 = 3


physics at fermilab


All mixed up

Important SM relations

– Mixing characterized by an angle, θW

(“Weinberg” or “weak” angle)

–

θW can be measured many ways…in different reactions

γ = B0 cosθW + W 0 sinθW

Z = W 0 cosθW − B0 sinθW

e = gW sinθW

GF

2= gW

2

8MW

MW = 12

gW v ≅ 80 GeV / c2 ⇒ v ≅ 246 GeV

MZ = MW / cosθW ≅ 90 GeV / c2

T>Tc , a triplet of spin 1 bosons,W±0 and a singlet, A0 – T<Tc W0-A0 mix

MZ constrained byMW and θW

scale of EWSymmetry breaking

Electromagnetism mixed withweak interactions


physics at fermilab


First, working within a restrictive, successfulsingle model is unusual – it works too well.

Gauge symmetry – a good idea … but why:– SU(2) x U(1) hard-wired to account for known weak

and electromagnetic phenomena. Higher symmetry?

Symmetry breaking– What is the character of the breaking?

Quarks-leptons?– Pattern looks suspicious, right? Why?

– 3 sets? Z decay & astrophysics suggest “yes”

– Substructure? Stringyness?

Fermion mixing– Why is there matter and not Antimatter?

– Do neutrinos also mix, and hence have mass?

Why and how is there mass?– Thought to be induced by the Higgs field…

• Ubiquitous, fills the vacuum acting almost like aviscous medium

• The Cooper Pair of the particle ground state

Gravity

Standard Model–what we don’t know


physics at fermilab


Masses

so, what is it with mass, anyhow?

10 100 150 2001 50

up: 0.1 GeV/c2

strange: 0.3 GeV/c2

charm: 1.5 GeV/c2

bottom: 4.5 GeV/c2

top: 175 GeV/c2

electron: 0.0005 GeV/c2

e neutrino: 0

muon: 0.1 GeV/c2

µ neutrino: 0

tau: 1.7 GeV/c2

τ neutrino: 0

gluon: 0

photon: 0

W: 80 GeV/c2

Z: 91 GeV/c2

Higgs: > ~ 86 GeV/c2 from LEP

down: 0.1 GeV/c2

250

EW symmetry breakingscale…eh? eh??

favoredLogically heavier okay


physics at fermilab


The vertices

Feynman diagrams for vertices (fermioninteractions)

Neutral electroweak

−ie

sinθW cosθW

1

2γ µ

1 −γ 5

2

−ieQ jγµδ ij

−igW

2γ µ (1 − γ 5 )

Charged electroweak

Strong

−igS

λα

2γ µ

Higgs

−ie

2 sinθW

m f

MW


physics at fermilab


New physics is in the loops

IVB Propagators contain the hints

Contribution ~ m 2top / M 2W)How we knew where to look then

Contribution ~ ln(m 2Higgs / M 2W)How we know where to look, now


physics at fermilab


HEP around the world

7 laboratories in the world dedicated to HEP– In the US: SLAC (e+e-); CESR (e+e-); Fermilab (pp &

assorted)

– In Europe: CERN (e+e-); HERA (ep); DAΦNE(e+e-)

– In Asia: BEPC(e+e-); KEK (e+e-)

Future facilities are:– In the US: PEPII1999(e+e-); CESRII1999(e+e-); Fermilab

MI2000(pp)

– In Europe: LHC2007(pp)

– In Asia: KEKB1999(e+e-)

The U.S. will lose the lead unless we figure outhow to build a facility beyond LHC, 2010

Imagined facilities include:

– In US: NLC(e+e-); muon collider(µ+ µ -); VLHC(pp)

– In Europe: NLC(e+e-), τ charm(e+e-)

– In Asia: NLC(e+e-)

To probe the important questions we get together with400-500 of our closest friends and perform experiments

at just a few international facilities.

To probe the important questions we get together with400-500 of our closest friends and perform experiments

at just a few international facilities.


physics at fermilab


HEP around the world, today.

SLAC e+e-

Fermilab pp

CERN e+e-

Cornell e+e-

KEK e+e-

BEPC e+e-

DESY ep

DAΦNE e+e-


physics at fermilab


Some jargon: pT - transverse momentum (conserved)η - pseudo rapidity [ = ln(tan(θ /2)]

σ - barn (1b = 10-28 m2)

L - instantaneous luminosity #/cm2 s, N = σ L TL - integrated luminosity, [ = ∫ L dt ]

A dictionary & the calendar

• The currency at Fermilab is L in pb-1 and fb-1

To set the scale:

σtotal(inelastic) ≈ 50 mb; σ(W eν) ≈ 2 nb; σtotal(tt) ≈ 6 pb

• The first run of the Tevatron collider with bothdetectors was:– Run I 1993-1996: 100 pb-1

• 3 periods, 1a, 1b, and 1c• Center of mass energy: 1.8 TeV (plus 630 GeV)

• The next running will start soon – and go a while– Run II 2000-2003? 1-3 fb-1

• A few periods• Center of mass energy: 2 TeV

– Run III? 2003-2008? 30 fb-1

• many periods• Center of mass energy: 2 TeV


physics at fermilab


Accelerator Complex - the time machine

A mixture of future technologies

Tevatron

LinacBooster

Main InjectorPbar Accumulator

(Extracted beams)


physics at fermilab


Fermi National Accelerator Laboratory

New accelerator(s):Main Injector

Central labfacility

antiprotons protons

1 m

ile

CDFexperiment

CDFexperiment

DOexperiment


physics at fermilab


DO detector, Y1.999k

• magent: 2T, 60cm x 2.8msuperconducting solenoid

• tracking: ∆pT/pT ≤ 5% for

pT=10 GeV/c muons, η < ~1.8

1) Si: 4 layer barrels(dbl/sgl) & dbl-sided disks(|η | ≤ 3), 0.8M ch.

2) SciFi: 8 layers ribbondblets, 77k ch. w/VLPCreadout

3) preshower: central (η <~1.5), 6k ch./fwd, 16k ch.

• muons: forward and central

1) central: faster gas;deadtimeless; bottomscint.; φ trg scint

2) forward: timing/trk-matching pixel cntrs; 3layer prop min-drift

• trigger: significant upgrade

1) 10kHz L1; 1KHz 100µs

L2; 100ms 50 Hz L3

• all significant upgrades


physics at fermilab


CDF detector, Y1.999k

• tracking: significant upgrade

1) Si: 5 layer, dbl sided strips

(|η | ≤ ~2.5); ISL strips

(1 ≤ |η | ≤ 2)

2) outer: smaller, open-cell COT drift chmbr. 180µ m

3) Si vertex trigger (SVT)• calorimeter: significantupgrade, forward

1) endplug: (1.1 ≤ |η | ≤ 3.6), scint. tiles w/ WLS fiber

readout• muons: moderate upgrade

1) intermediate muon system• trigger: significant upgrade

1) 50kHz L1; 0.3KHz 20µs L2; 50 Hz L3


physics at fermilab


Run 1 performance

Accelerator performance 900 GeV/beam was staggering

Designed for 1x10 30 s-1cm-2; actual: ≤ 1.6x1031 s-1cm-2

Designed for: ∫Ldt ~ 5pb-1 ; actual: ∫Ldt ~ 110 pb-1

900 GeV/beam; 6 bunches; 3.5 µs between bunches

1-3 int/crossing (important)


physics at fermilab


0.1

1

10

100

1030 1031 1032 1033 1034

Mean Interactions/crossingin

tera

cti

ons/c

rossin

g

instantaneous luminosity (per cm 2 s)

“ tev_2000 ” accelerator assumptions:—Run II: commissioning, late 1999 with physics, 2000 2002?

—2 TeV @ ≤ 2 x 1032 cm-2 s-1

—396ns - 132ns bunch spacing—2fb-1 to tape

Run III: Tev33: 2003 - ?

...LHC underway ? 2006? 7?

...something cool happens?

2 TeV @ ≤ 1033 cm-2 s-1

dynamically adjusted β * ?

~25-30% int. loss†

132ns bunch spacing30fb-1 to tape

Run 2 and beyond

1992-31994-5

load-levelingtrigger?

6 bunches

36 bunches

108 bunches

2000 ?

2001 ?

Run 1b, >2 int/crossing


physics at fermilab


Run I physics, a (tiny) snapshot

Top quark– Discovery!– mt = 174.3 ± 3.2 (stat) ± 4.0 (sys) GeV/c 2

• Beginnings of detailed studies (cross sections,distns, BR, etc.)

W/Z bosons– MW = 80.45 ± 0.063 GeV/c 2

– V-V-V couplings studied

– W/Z + soft gluon radiation

Bottom quarks – a new field

– 100’s B J/Ψ- KS

– BC discovered

– Production σ’s & BR’s

Quantum Chromodynamics– Substructure probed, 10-18 cm

– Radiative corrections confirmed

– Colorless exchange - Pomeron

Exotic physics – searches– supersymmetry

– leptoquarks

– Higgs boson

– additional W/Z’s

unanticipatedprecision

Over 250 papers published inPRL, PR, NP

Over 250 papers published inPRL, PR, NP


physics at fermilab


The decay of a quark, Q, with mQ > MW + mq is straightforward:

Vtb is an element of the quark mixing matrix, bounded by the requirement ofUnitarity and weak interaction phenomenology.

SO, the fraction of decay of t W b is almost 100%.SO, τ top ≈ 0.4 x 10-24 s … QCD confinement scale ≈ 1/ΛQCD ≈ few x 10-24 s

Which means…top quarks decay before they form top-mesons…barefermion… unprecedented and surely a clue to something?

Vud Vus Vub

Vcd Vcs Vcb

Vtd Vts Vtb

≈

0.9745 − 0.9760 0.217 − 0.224 0.0018 − 0.0045

0.217 − 0.224 0.9737 − 0.9753 0.036 − 0.042

0.004 − 0.013 0.035 − 0.042 0.9991 − 0.9994

The TOP quark, 1

Who ordered that? – the extraordinary massdistorts one’s normal picture of a quark...

90% qq and 10% gg for pp

Γ(Q → qW+ ) =GFmQ

3

8π 2Vtb

21−

MW2

mQ2

2

1 +2MW

2

mQ2

One power of GF


physics at fermilab


The TOP quark, 2

Getting to the bottom of the top quark…

– The b quark lives a long time…τb ≈ 1.5 ps

Si vertex detectors are magic

Can tag the presence of b quarks

– Efficiency for 1 Si vertexing (SVX) tag is ε ~50% and

essentially p(b) independent

– Can double tag with ε > 40%

– also can detect the presence of a soft lepton (SLT) fromb c l ν

• long enough to measure• Important for top physics• now a precision industry

CDF


physics at fermilab


The TOP quark, 3

Manifests itself three ways:

Huge backgrounds: QCD multijets w/ S/B~1/1

bqq’ bqq’ 44% “dijet”

blν blν 5% “dilepton”

blν bqq’ 30% “lepton + jets”

Charged leptonMissing energy2 jets2 b quarks

serious backgrounds: QCD Wjjbb w/ S/B~2/1, 4/1 with b tagging

But wait, there’s more:

low backgrounds: QCD Wjjbb, (fake e,missing j) w/ S/B~3-4/1


physics at fermilab


Top, revealed

t W (eν )b

t W (qq)b

DO


physics at fermilab


Top’s bare bottom revealed

CDF


physics at fermilab


Top quark physics: cross section

A complicated theoretical effort for comparison– Stresses QCD understanding at a deep level

– Heavy quark QCD is tough

CDF: 7.6 pb DO: 5.9 ± 1.7 pb

+ 1.8- 1.5


physics at fermilab


Top quark physics: mass determination

Full kinematical fitting of lepton+jets, dilepton, alljets candidates– A serious challenge for background simulation

– The QCD production of W+ multiple jets w/b’s

Very sophisticated likelihood combinations ofsamples are now done– eg., CDF combined 4 indepdendent samples for their

best result

– DO employs complicated kinematical and topologicalcuts

Channel DO DO CDF CDFsample bckgnd sample bckgnd

Di-lepton 5 1.4 ± 0.4 9 2.4 ± 0.5Lep+jets SVX 34 9.2 ± 1.5Lep+jets SLT 11 2.4 ± 0.5 40 22.6 ± 2.8Lep+jets top 19 8.7 ± 1.7All jets 41 24.8 ± 2.4 184 142 ± 12eν 4 1.2 ± 0.4

eτ, µτ 4 ≈2


physics at fermilab


Lepton plus jets mass results

CDF

DO

Systematics (GeV/c2):Jet energy det 4.4FSR 2.2ISR 1.8Bckgnd shape 1.3btag bias 0.4pdf 0.3Total 5.3

Systematics (GeV/c2):Jet energy det 4.0Bckgnd model 2.5Signal model 1.9Fitting tech 1.5Cal noise 1.3Total 5.5


physics at fermilab


mt results

Top Quark Mass

mt = 174.3 ± 5.1 GeV/c 2


physics at fermilab


ElectroWeak Interactions

The physics of W’s, γ’s, and Z’s

σ (W,Z) & ΓW determination

– “tri-boson couplings”• Testing the gauge theory at the vertices – newphysics would reveal itself here

– Mass determination (remember the loops?)• Requires precision of ±0.06% Cross section –strong test of QCD

–Theoretical prediction: O(α 2S)

Hamberg, van Neerven, Matsuura;van Neerven & Zijlstra

Dominant uncertainties:Luminosity, ≈ 8% & Parton distribution functions, ≈ 3%


physics at fermilab


W mass determination

A tricky measurement

Isolated leptonMissing momentum

d) σ

dmT2 =

Vqq'2

4πGFMW

2

2

21

) s − MW

2( )2+ ΓW MW( )2

2 − mT2 ) s

1 − mT2 )

s ( )1/2

mT2(l,νl) =

r p l +

r p ν l( )2

−r p l +

r p ν l( )2

= 2ETlET

ν l 1 − cosφlν( )

Moderate hadronic recoil (~5 GeV/c)

2 body decay kinematicsdefine “transverse mass”

DO latest

MW = 80.474 ± 0.093 GeV/c2 DO = 80.433 ± 0.079 GeV/c2 CDF = 80.450 ± 0.063 GeV/c2 Tevatron


physics at fermilab


Remember, if you don’t see anything,it’s a neutrino...

DO W eν


physics at fermilab


RW / Z =

σ W ⋅ BR(W → lνl )

σZ ⋅ BR(Z → ll)=

σ W ⋅ Γ(W → lνl)

σ Z ⋅ BR(Z → ll) ⋅ ΓW

The full width of the W can be measured in threeways (SM: ΓW = 2.077 ± 0.014 GeV)

– Indirectly from:

– Directly from the tail of the mT distribution:

– Simultaneously, in 2 parameter fit with MW

ΓW

ΓW = 2.130 ± 0.56 GeV DO (new)

= 2.064 ± 0.084 GeV CDF

ΓW = 2.130 ± 0.56 GeV DO

= 2.064 ± 0.084 GeV CDF

ΓW = 2.19 ± 0.19 GeV CDF


physics at fermilab


Tri-boson couplings

The IVB can couple to one-another due to thenon-Abelian nature of the Yang-Mills prescription

Measurements characterized as parameterized deviations fromSM...an anomolous magnetic or electric momentStandard Model values: κγ, Z = 1; λγ, Z = 0; hZ,γ

1-4 = 0

hZ,γ1-4

κγ, Z , λγ, Z

CDF preliminary

DO

– 0.93 < κ γ -1 < 0.94

– 0.31 < λ γ < 0.29

DO

CDF preliminary

– 1.8 < κ γ -1 < 0.94

– 0.7 < λ γ < 0.6

DO + LEP @ 68% CL∆κ γ = 0.13 ± 0.14

λ γ = 0.6 ± 0.07


physics at fermilab


The Standard Model Connection

• LEP2 has announced resultsfrom 183 GeV running (lastweek)

• NuTeV (ν N DIS) has

preliminary resultssin2θW, interpreted as MW

IT’S A DIFFERENTGAME NOW –THE SM HIGGSBOSON APPEARSTO BE LIGHT

IT’S A DIFFERENTGAME NOW –THE SM HIGGSBOSON APPEARSTO BE LIGHT

Run2 uncertaintiesintentionally plotted @1996 central valuesGood reminder of what 1 σmeans & reason forgrowing excitement atFermilab


physics at fermilab


Quantum Chromodynamics

Study of strong interactions– Both basic and very complicated

phenomenology–rich field

Most basic measurement–thesearch for substructure…akinto the original discovery ofpartons at SLAC

Controversial for a while: was therean excess at high jet E T?could be evidence for substructure

False alarm? Both experimentsagree…both agree with theory. Probablya reminder of how hard it is to predict thegluon distribution in the proton


physics at fermilab


Highest ET jet event in DO ET = 475 GeV


physics at fermilab


QCD

Much more…– Dijet mass spectrum - another substructure search

Excess would suggest a new length scale in 2

parton collisions

From CDF inclusive jets: Blue shows the running of the strong coupling, αS(E), with

changing scale, ET. Red, shows the lack of dependence at a fixed scale. Not absolute αS(E).

• α S running determination

CDF

at an electron collider …at a hadron collider!


physics at fermilab


QCD

Gluons are cheap…– Indeed, they radiate like mad from quarks and gluons

and accounting for them is complicated in processes inwhich there are two length scales

• eg, the dσ /dpT for W and Z production, or γγproduction

Must deal with ∞ series ofdivergences: ln(Q 2/p 2T)

Turn-over, theeffect of QCDradiativecorrections andinfinite gluonresummation

DO preliminary


physics at fermilab


B Physics – HEP with microbarns

Both experiments study B mesons

CDF’s SVX tags the detached vertices of the B’s

• Largest sample in the world.

Forward productionagrees with centralproduction


physics at fermilab


B ut wait, there’s more

CDF: lifetimes, eg.

CDF discovered the BC meson

M(Bc) = 6.40 ± 0.39 ± 0.13 GeV/c2

τ (Bc) = 0.46 ± 0.05 ps+0.18- 0.16

BC± J/ψ l X

bound (bc)

τ (B-) = 1.637 ± 0.058 +0.045/-0.043 ps

τ (B0) = 1.474 ± 0.039 +0.052/-0.051 ps

τ (B0s) = 1.34 + 0.23/-0.19 ± 0.05 ps

τ (Λ0b) = 1.36 ± 0.09 +0.06/-0.05 ps Λb Λc l ν

B J/ψ Κ & D l XBs J/ψ φ

• CDF observed and measured B0 - B0 oscillationparameters

Combination of 3 tagging techniques:SVX “same side” tagSLT tagJet charge tag

B J/ψ Κ0s

sin2β = 0.79+ 0.41– 0.44

Where the SM predicts 0.66 - 0.84First observation of CP in the Bsystem, confirming the largeexpected asymmetry


physics at fermilab


the zoo

Many extensions of the SM are imaginable– All must be dealt with systematicallyExotica including:Extra gauge bosonsLeptoquarks (bound lepton-quark states)Technicolora matter of luminosity...

Measured limits are right on schedule for 100 pb-1

1996 prediction


physics at fermilab


Goals of Run II

Accelerator:– To deliver 10-30 x more integrated luminosity

Experiments:– To deal with it...and the required upgrades

Physics goals:

– Understand the top quark, measure δ mt ≈ 3 GeV/c2

– Determine the cross section to ± 8%

– Determine the W mass to δ MW ≈ 40 MeV/c2

– Determine the W width to few %

– Determine | Vtb | to ±10%

– Refine B physics measurements, extend rare decaysearches

– Extend the reach for compositeness to 500 GeV

– Test NNLO QCD and further study the pomeron

– Extend the search reach for Supersymmetry and exoticphenomena


physics at fermilab


Top quark physics in the future

accepted/experiment

mode 2fb-1 10fb-1

tt produced 16,000 80,000

l + ≥ 3j / 1b tag 1,800 9,000

l + ≥ 4j / 2b tags 600 3000

l l + 2j 200 1,000

EW produced top 330 1,650

With ∫Ldt = 10 fb -1, we will:•determine mtop to 1-2 GeV/c2

•measure σ (tt) to 6%•measure BR(t → b) to 5%•probe for tt resonant states to

1 TeV/c2

•Michel analysis of top couplings•isolate EW produced top quarks and:

determine σ to 10%determine Γ(t →Wb) to 10%determine V tb to 5%search for anomalous couplingssearch for CP

•probe for rare decays to 10 -3 - 10-4

With ∫Ldt = 10 fb -1, we will:•determine mtop to 1-2 GeV/c2

•measure σ (tt) to 6%•measure BR(t → b) to 5%•probe for tt resonant states to

1 TeV/c2

•Michel analysis of top couplings•isolate EW produced top quarks and:

determine σ to 10%determine Γ(t →Wb) to 10%determine V tb to 5%search for anomalous couplingssearch for CP

•probe for rare decays to 10 -3 - 10-4

Fermilab is atop quark factory

The TOP might beSpecial…we aim tofind out.


physics at fermilab


IVB physics

With ∫Ldt = 10 fb -1, we will:

determine MW to ~30 MeV/c 2

– which will bound MH to 40-50% of itself– (good timing for direct searches)

measure Γ(W) to 15 MeV

refine asymmetries ( W and Z) and hence, pdf’s

limit WWV and Zγ couplings

quantify radiation zero in Wγ

search for rare W decayslimit CP violationquantify quartic gauge couplingsstudy resummation in 2 scale problems

– pT(W), pT(γγ)

With ∫Ldt = 10 fb -1, we will:

determine MW to ~30 MeV/c 2

– which will bound MH to 40-50% of itself– (good timing for direct searches)

measure Γ(W) to 15 MeV

refine asymmetries ( W and Z) and hence, pdf’s

limit WWV and Zγ couplings

quantify radiation zero in Wγ

search for rare W decayslimit CP violationquantify quartic gauge couplingsstudy resummation in 2 scale problems

– pT(W), pT(γγ) accepted/experimentchannel 2fb-1 10fb-1

W→eν 1.6M 8M

Z→ee 160k 800k

Wγ 1000 5000

Zγ 300 1500WW 100 500WZ 40 400ZZ few 30

Fermilabis a vector bosoncraft-workshop


physics at fermilab


QCD

With ∫Ldt = 10 fb -1, we will:Study the edge of phase space!Probe deep structure beyond 500 GeVMeasure IVB+jet production with high statisticsUnderstand multi-scale physicsUnderstand multi-gluon physicsHeavy quark production kinematics/dynamicsProbe jet structureUnderstand multi-jet kinematicsNNLO calculational comparisonUnderstand diffractive scatteringSupport all other collider analyses with crucial

background studies

Search for new phenomena!

With ∫Ldt = 10 fb -1, we will:Study the edge of phase space!Probe deep structure beyond 500 GeVMeasure IVB+jet production with high statisticsUnderstand multi-scale physicsUnderstand multi-gluon physicsHeavy quark production kinematics/dynamicsProbe jet structureUnderstand multi-jet kinematicsNNLO calculational comparisonUnderstand diffractive scatteringSupport all other collider analyses with crucial

background studies

Search for new phenomena!

Fermilab is aQCD conglomerate

Millions of events,period.


physics at fermilab


B physics

With ∫Ldt = 2 fb -1, we will:Measure CP violation in three modes

B0 J/ψKs

B0 ππ

B0 J/ψφ

Measure | V td | / | Vts | from BS mixing & ∆Γs

Refine rare decay searches

B µµK

B µµK*

Bd µµ

Bs µµ

Completely understand the B C system

Completely understand B s mixingSemileptonic decaysFully hadronic decays

With ∫Ldt = 2 fb -1, we will:Measure CP violation in three modes

B0 J/ψKs

B0 ππ

B0 J/ψφ

Measure | V td | / | Vts | from BS mixing & ∆Γs

Refine rare decay searches

B µµK

B µµK*

Bd µµ

Bs µµ

Completely understand the B C system

Completely understand B s mixingSemileptonic decaysFully hadronic decays

accepted/experimentchannel 2fb-1 10fb-1

B mesons 1010 5x1010

B baryons 108 5x108

Bc 109 5x109

B0 J/ψKs 15,000 75,000

Fermilab is abottom quark industry


physics at fermilab


There’s more

Multiple inverse fb make a qualitativedifference:

Supersymmetry

and

the Anderson-Higgs Boson

are accessible before the LHC


physics at fermilab


Supersymmetry–in words

The SM is extraordinarily successful– nothing seems out of line…yet nobody is happy.

Digging deeper is troubling– The SM describes physics of the scale of the W/Z

masses ~ 100 GeV, or distances of ~ 10-18cm

– What about deeper scales? What are scale-milestones?

• Higgs is fat, due to radiative corrections– The “Hierarchy Problem” is due to quartic self-

interactions

H H HHThe only high energy scale is the Planck scale of 1018 GeVSo, the counter term must cancel to one part in ~ 1016

Ugly...the SM is fundamentally sick

one loop contribution to the mass

Suppose the theory has Higgs’, fermions, and additional scalars

MH2 ~ MH 0 +

λ4π 2 Λ2 +δMH

2

MH

2 ~ MH 02 +

gF2

4π 2 Λ2 + mF2( ) −

gS2

4π 2 Λ2 + mS2( ) + logs +K

Relating the regular fermions and the new scalars requires asymmetry between them so that the Λ terms cancel

SUSY provides that connection: S| F > = | B >


physics at fermilab


In practice, difficult

Supersymmetric partners for all particles– With a spin flip…and a cute s-prefix

• Electron (spin 1/2) becomes selectron (spin 0)• Quark (spin 1/2) becomes squark (spin 0)• Photon (spin 1) becomes photino (spin 1/2)• Gluon (spin 1) becomes gluino (spin 1/2)

– No SUSY at low energies, so supersymmetry isbroken…search for their interactions at higher energies

This is not just silly…– The Higgs mechanism is accounted for in a natural way

and the Weinberg angle is predicted

– Unification of forces appears to work

– Superstrings contain SUSY...

A bold theoretical suggestion, on par with Dirac’spositron, or Weinberg’s Z !!


physics at fermilab


SUSY provides a unification ofcouplings

•Unification – a goal – requires serious tinkering•Each force (electromagnetic, strong, and weak) is characterizedby a coupling, α i(q) (I = 1,2,s), for

2 EW couplings and 1 QCD coupling•Unification requires that α 1(MX) = α 2(MX) = α s(MX)

α s

α 2

α 1Modern analysessuggest α s≈ 0.13


physics at fermilab


Seeking SUSY

SUSY is not the only solution…– composite Higgs can protect itself from infinities

(technicolor)

However, it is taken very, very seriously– Many flavors of models…thousands

– A particular brand is especially promising, called theMinimal SuperSymmetric Model (MSSM) containsdefinite predictions• 4 Higgs bosons, one of which is SM-like and mustbe lighter than ≈ 125 GeV/c2

• A supersymmetric “number” is conserved, sodecays of SUSY particle result in another SUSYparticle

• A mass spectrum is conceivable, so there is asterile Lightest SUSY state…which is missingenergy in a detector

• Signals are many leptons, and/or jets withsignificant missing energy


physics at fermilab


The time is right...

Model space

Run IIRun III

you are here

trilepton search

-ino Predicted actual

Run I 2fb-1 10fb-1 Run I

χ± 65 ~220 235 70

g 170 ~360 400 270

t1 48 150 155 145

Fermilab could be aSUSY venture startup…

Dozens of limitshave been setalready by bothexperiments


physics at fermilab


The HIGGS is the thing...

The Higgs couples to fermions via mfBig is beautiful..

we expect a light SM Higgs to decay overwhelmingly to bpairs, or 2W’s if slightly heavier...

The GoldenMode

Remember the EW connection? The SM seems to be pointing

to a light Higgs boson

For which there is rate~


physics at fermilab


Higgs could be ours...

Needs:– Luminosity

– Ability to tag b’s of relatively high pT

– Ability to form M(bb) with good resolution

B tagging efficiencies arealready thereWill be better in Run II

CDF

2fb-1

potentiallybetter than“nominal”

CDF: Z bb CDF MC extrapolation to Run I


physics at fermilab


Higgs will be surrounded

M(bb) in 10 fb-1

δM ≈ 8 GeV

S/B ≈ 1/1, dependent on cutsMass resolution is key

top eventsZ bb

Run II

Run III

WH region

WW region

Recently, a year-longworkshop at Fermilab:

Fermilab could be aHiggs cottage industry


physics at fermilab


The plan is clear...

Run II– Provides an ability to take the top quark apart

– Uncover CP violation in the B system

– Determine the W mass to precision necessary to cornerthe Higgs

Run III, above a critical L threshold of about 20pb-1

– Will possibly discover SUSY

– Should discover the Higgs Boson• If not there, then the more promising SUSY modelis wrong, the SM EW model will be in jeopardy,

–and a whole new era in elementary particlephysics will have opened.

• If it is there, it will be studied at LHC, NLC, and/ora µ collider

–and a whole new era in elementary particlephysics will have opened.


physics at fermilab


Conclusion

I’ve not talked about the Kaon CP program or theneutrino oscillation program

We are guaranteed a Complete Program

programmatic, evolutionary measurements blended withsignificant discovery potential

Fermilab is the place tofollow the connections.

Taken together…This is a great time to be at Fermilab

Millennial Physics at Fermilab - Michigan State University · Chip Brock, Michigan State University...

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