Minimal Electroweak Scale Cosmology and the LHC M.J. Ramsey-Musolf Wisconsin-Madison NPAC...
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Transcript of Minimal Electroweak Scale Cosmology and the LHC M.J. Ramsey-Musolf Wisconsin-Madison NPAC...
Minimal Electroweak Scale Cosmology and the LHC
M.J. Ramsey-MusolfWisconsin-MadisonQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
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http://www.physics.wisc.edu/groups/particle-theory/
NPACTheoretical Nuclear, Particle, Astrophysics & Cosmology
Berkeley, March 2009
Outline
I. Intro & Motivation
II. Baryogenesis & EWPT
III. Three minimal models & their LHC phenomenology
• Real Singlet xSM
• Complex Singlet cxSM
• Real Triplet SM
V. Barger, P. Fileviez Perez, H. Patel, P. Langacker, M. McCaskey, D. O.Connell, S. Profumo, G. Shaugnessy, K. Wang, M. Wise
Minimal TeV-scale SM extensions
• Can help explain the origin of matter (visible and dark)
• Can be discovered at the LHC
• Can be probed in cosmologically relevant parameter space at colliders
Cosmology at the HEP & NP Interface
• Nature of DM & its interactions
• Origin of the BAU
Two puzzles:
Additional problems:
• Gauge hierarchy
• EWPO & mH (little hierarchy)
• Origin of m
Indirect & direct detection
Collider E
Collider: EWPT & spectrum
EDM: CPV
Non-minimal Solutions (SUSY)
Nature of DM & its interactions
Origin of the BAU
Gauge hierarchy
EWPO & mH
Origin of m
“Minimal” : 105 new parameters
Additional complications:
• Why is ~ Mweak ?
• Why little flavor & CPV ?
• Origin of params in Lsoft ?
• MSUSY < TeV (hierarchy)
• Bino-Higgsino-like LSP (DM)
• Light RH stop ( m < 125 GeV)
• M1 ~
Minimal Solutions (non-SUSY)
Nature of DM & its interactions
Origin of the BAU
Gauge hierarchy
EWPO & mH
Origin of m
Extra Scalars Extra Fermions
• Set aside hierarchy problem (for now)
• To what extent can minimal scenarios for new electroweak scale physics help explain the abundance of matter (visible & dark) ?
• How can they be probed at the LHC ?
This Talk
Highlight for This Talk: Scalars
Gauge Interactions
No Gauge Interactions
Simplest: 1 new dof
Next Simplest: 2 new dof
Focus: Key parameters for cosmo & LHC pheno
Complex Singlet (cxSM):DM, BAU, and mH / EWPO
H-S Mixing, Reduced BRs, & SI
Real Singlet (xSM):DM or BAU-mH / EWPO
BAU: H-S Mixing & Reduced BRs
DM: Reduced BRs & SI
Simplest: 3 new dof (2HDM: 4 new dof)
Real Triplet SM)DM or BAU (EWPT)
DM: Charged track & SI
BAU: or bb; Br(H!)
Baryogenesis: Ingredients
Anomalous B-violating processes
Prevent washout by inverse processes
Sakharov Criteria
• B violation
• C & CP violation
• Nonequilibrium dynamics
Sakharov, 1967
SM Sphalerons:
SM CKM CPV:
SM EWPT:
EDMs
LHC: Scalars
Electroweak Phase Transition & Higgs
?
φ
?
φ
?
F
?
F1st order 2nd orderLEP EWWG
Increasing mh
mh>114.4 GeV
or ~ 90 GeV (SUSY)
Computed ESM : mH < 70 GeV
Need
So that sphaleron is not too fast
EMSSM ~ 10 EpertSM : mH < 120 GeV€
€
€
˜ t
€
+LStop loops in VEff
Light RH stop w/ special
Non-doublet Higgs (w / wo SUSY)
€
S
€
Mixing€
S
€
€
S
Decay
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The Simplest Extension
Model
Independent Parameters:
v0, x0, 0, a1, a2, b3, b4
H-S MixingH1 ! H2H2
€
M 2 =μh
2 μhs2 2
μhs2 2 μ s
2
⎛
⎝ ⎜
⎞
⎠ ⎟
Mass matrix
€
h1
h2
⎛
⎝ ⎜
⎞
⎠ ⎟=
sinθ cosθ
cosθ −sinθ
⎛
⎝ ⎜
⎞
⎠ ⎟h
s
⎛
⎝ ⎜
⎞
⎠ ⎟
Stable S (dark matter?)
• Tree-level Z2 symmetry: a1=b3=0 to prevent s-h mixing and one-loop s hh
• x0 =0 to prevent h-s mixingxSM EWPT:
Signal Reduction Factor
Production Decay
€
e+
€
e−
€
Z 0
€
Z 0
€
€
S
sin2
Simplest extension of the SM scalar sector: add one real scalar S
• Goal: identify generic features of minimal models with new scalars having a strong, 1st order EWPT and/or DM
• Determine low-energy phenomenology (Higgs studies, precision ewk)
• Address CPV with a different mechanism
Finite Temperature Potential
?
φ
?
φ
?
F
?
F
€
H 0
€
S
• What is the pattern of symmetry breaking ?
• What are conditions on the couplings in V(H,S) so that <H0>/T > 1 at TC ?
Cylindrical Co-ordinates
€
€
α • Compute Veff (αT )
• Minimize w.r.t α
• Find TC
• Evaluate v(TC )/TC ~
cos α(TC) (TC )/TC
VEFF (T) & EWSB
Potential
Key Parameters
Analytic
Analytic
Numerical€
h2
€
h1
€
h2
€
e+
€
e−
€
Z 0
€
Z 0
€
€
S
Strong first order EWPT: SMStrong first order EWPTIncrease
Large e < 0
Reduce
Nonzero V0
a1<0, a2 either sign
Light: all models Black: LEP allowed
a1=b3= 0, a2 < 0
Symmetry Breaking
Two Cases for <S>at high T:
?
φ
?
φ
?
F
?
F
€
H 0
€
S
€
€
α
Vmin = 0
Vmin = V0 < 0
LHC Phenomenology
Signatures
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EWPO compatible
m2 > 2 m1
m1 > 2 m2
LHC: reduced BR(h SM)
€
h1
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h2
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h1€
b
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b
€
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Signal Reduction Factor
Production Decay
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CMS 30 fb-1
SM-like
Singlet-like
SM-like
SM-like w/ H2 ->H1H1 or Singlet-like
~ EWB Viable
Light: all models Black: LEP allowed
Scan: EWPT-viable model parameters
LHC exotic final states: 4b-jets, + 2 b-jets…€
h2
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h1
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h2
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EWPO comp w/ a1=0=b3
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LHC: reduced BR(h SM)
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Probing : WBF
H ! ZZ! 4 l
H ! WW! 2j l
• Early LHC discovery possible
• Determine as low as ~ 0.5
Complex Singlet: EWB & DM
Barger, Langacker, McCaskey, R-M, Shaugnessy: 0811.0393 [hep-ph]
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Key features for EWPT & DM: (1) Softly broken global U(1)
(2) Closes under renormalization
(3) SSB leading to two fields: S that mixes w/ h and A is stable (DM)
Controls CDM& EWPT
No domain walls DM mass
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No CPV for T < TEW : Stable A
Spontaneous CPV for T ~ TEW ?
Complex Singlet: EWB & DM
Barger, Langacker, McCaskey, R-M, Shaugnessy 2 controls CDM& EWPT
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MH1 = 120 GeV, MH2=250 GeV, x0=100 GeV
Complex Singlet: Direct Detection
Barger, Langacker, McCaskey, R-M, Shaugnessy Two component case (x0=0)
Little sensitivity of scaled SI to
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Complex Singlet: LHC Discovery
Barger, Langacker, McCaskey, R-M, Shaugnessy
Traditional search: CMS
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Invisible search: ATLAS
Single component case (x0 = 0)
EWPT
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h j
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A
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VBF: Invisible Search I
Central Jet Veto
H ! W+W- ! jj : ideally only W decay products in central region (Chehime & Zeppenfeld ‘93)
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H ! W+W- ! l + l - : central region minijet from SM bcknd, separation from dilepton pair (Barger, Phillips, Zeppenfeld ‘94)
VBF: Invisible Search II
pT (H) distribution
Look for azimuthal shape change of primary jets (Eboli & Zeppenfeld ‘00)
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Large pT (invisible decay)
Dijet azimuthal distribution
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Cahn et al ‘87
Complex Singlet: LHC Discovery
Barger, Langacker, McCaskey, R-M, Shaugnessy
Traditional search: CMS
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Invisible search: ATLAS
Single component case (x0 = 0)
EWPT
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h j
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A
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A
Combined search
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Real Triplet
~ ( 1, 3, 0 )
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Independent Parameters:
v0, x0, 0, a1, a2, b4
Fileviez-Perez, Patel, Wang, R-M: 0811.3957 [hep-ph]
Real Triplet : Key Features
Gauge interactions
Large ! W+W- : Need M ~ 2 TeV for full CDM
parameterSmall x0(T=0) : Small mixing & EWPO impact
“Fermiophobic”1st order EWPT ?
SpectrumFour scalars : H1 ~ SM-like; H2 ~ triplet-like; H+, H-
Couplings & 2BRs
H1H+H- & H2W+W- : Strong a2-dependence ! Sensitivity of BR(Hj!)
Real Triplet : Production
Pair production dominant
Assoc production suppressed€
qq → Z*,γ * → H +H−
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qq → W ±* → H ±H2
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Below WZ Threshold
Promising for LHC
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bb
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bb γγ
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→ l, πν
Promising for ILC
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W +W − ZZ
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W + Z t b
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H2π + t b
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H2π + W − Z
Above WZ Threshold
Real Triplet : H+ Decays
Charged: decay length
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Secondary vertex
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H ± → H2W±*→ H2π ±
Tiny x0 : pure gauge
DM Limit: x0=0 & c = 5.06 cm
Real Triplet : DM Search
Basic signature: Charged track disappearing after ~ 5 cm
SM Background: QCD jZ and jW w/ Z !& W!l
Trigger: Monojet (ISR) + large ET €
qq → W ±* → H ±H2
€
qq → Z*,γ * → H +H−
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Cuts: large ET hard jet One 5cm track
Cirelli et al:
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M = 500 GeV:
CDM ~ 0.1
Real Triplet : Charged BRs I
Charged: x0 dependence
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H ± → H2W±*→ H2π ±
Pure gauge
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H ± →W ±Z, f1 f 2 x0 suppressed
Real Triplet : Charged BRs II
Charged: x0 dependence
Below WZ Threshold
Above WZ Threshold
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H ± → H2W±*→ H2π ±
Pure gauge
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H ± →W ±Z, f1 f 2 x0 supressed
Real Triplet : General Search I
€
qq → W ±* → H ±H2
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qq → Z*,γ * → H +H−
Cuts: min pT()> 25 GeV max pT()> 50 GeV| | < 2.8 R > 0.4
Basic signature: (large x0) or b b (small x0)
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| M - MH2 | < 5 GeV
Identification:
For bb: b-tagging, pT(b)> 15 GeV, |(b)| < 3.0
For soft from hadronic decay ! Leptonic decay w/ 5 GeV < pT(l) < 40 GeV, |(l)| < 2.8, ET > 20 GeV,
edge of MT
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Real Triplet : General Search II
€
qq → W ±* → H ±H2
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qq → Z*,γ * → H +H−
Basic signature: or b b
a2 = 1, 0, -1 :
Small x0 :
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a2-dependence of H2W+W- coupling
Real Triplet : Couplings
H2 WW Coupling
H1 H+ H- Coupling:
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(H1!) depends on a2 via H+H- loops
(H2!) depends on a2 via W+W- loops
Real Triplet : Neutral BRs
Neutral: differences with SM Higgs & a2 dependence
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Different ratio of WW and ZZ, BRs
Real Triplet : H1 Decays
Neutral SM-like Higgs: H+ loops and BR ( H1!)
X0=0: DM case
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X0>0: EWPT case
Real Triplet : Summary
Parameters relevant for EWPT: x0 , a1 , a2
H+ mass & decays: x0 , a1 H1,2 WW coupling via : a2
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DM Search: ~ 50 events for CDM ~ 0.1 (M ~ 500 GeV); study BR(H1 !)
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Summary
Gauge Interactions
No Gauge Interactions
Simplest: 1 new dof
Next Simplest: 2 new dof Complex Singlet (cxSM):DM, BAU, and mH / EWPO
H-S Mixing, Reduced BRs, & SI
Real Singlet (xSM):DM or BAU-mH / EWPO
BAU: H-S Mixing & Reduced BRs
DM: Reduced BRs & SI
Simplest: 3 new dof (2HDM: 4 new dof)
Real Triplet SM)DM or BAU (EWPT)
DM: Charged track & SI
BAU: or bb; Br(H!)
Minimal TeV-scale SM extensions
• Can help explain the origin of matter (visible and dark)
• Can be discovered at the LHC
• Can be probed in cosmologically relevant parameter space at colliders