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CMS Higgs Results
Adi Bornheim Caltech
06.04.2014 1
A brief history of recent times
2014 2004 1994 1984 1974 1964
W & Z Boson t-quark H Boson
This talk : Summary of 29 CMS publications and many preliminary results. https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsHIG
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Peter Higgs
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
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The CMS Collaboration
06.04.2014 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
The LHC Accelerator
06.04.2014 4
20 MHz
Average 400 MHz
Pile up : 40 vertices, 14 jets, 2 TeV
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
1380 1.5 X 1011
4 TeV
0.8 X 1034
5 σ H discovery
Five production processes, cross section varying by factor >200. Nine different decay modes, varying by almost four orders of magnitude.
Any possible combinations of final state objects.
Cross sections and branching ratios
06.04.2014 5 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
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More than 300 CMS publications are evidence for a very good understanding of our detector, simulation and backgrounds.
https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResults
CMS SM Precision Measurements
Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 06.04.2014
06.04.2014 7
The CMS Detector
All Silicon Tracker, High resolution Crystal ECAL Brass-Scintillator HCAL 3.8 Tesla Magnet Drift Tube and Resitive Plate Chamber Muon System
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→WW
06.04.2014 8 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
HIG-13-023
H→WW
06.04.2014 9
Very large branching ratio, but large backgrounds. Missing energy in final state ⇒ poor mass resolution. Use RAZOR variables to optimize signal line shape.
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
HIG-13-023
H→WW
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Analysis in many event categories (ee, µµ, eµ, 0/1/2 jets)
Significance : 4.3 σ at 125.6 GeV, observed cross section µ=0.72+0.20
Signal yield from LHC Run 1 in clean categories (eµ 0/1 jet) order 100 events.
HIG-13-023
-0.18
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→WW - Mass
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Large variation of σ∗BR(H→WW) with mH at fixed signal strength.
Linear dependency of mR peak on mH with approximately constant resolution.
mH=125.5±3.8 GeV
HIG-13-023
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
mH=128.2+6.6 GeV -5.3
H→WW - Coupling and Spin
06.04.2014 12
Spin-parity JP=0+ favored against narrow JP=2+ or JP=0-
Production cross section consistent with SM
Coupling consistent with SM expectation.
µ ggH
µVBF,VH
κ f
κV
HIG-13-023
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ZZ→4l
06.04.2014 13
HIG-13-002
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ZZ→4l
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At low Higgs masses steep drop of acceptance x efficiency.
Analysis challenge : Low pT lepton acceptance and performance.
HIG-13-002 Mass Resolution H→ZZ→4e
Muon Mass Scale acceptance x efficiency H→ZZ→4l
∆m < 0.1%
σE=2.0 GeV
Clean, narrow peak over a modest, well simulated background. Significance of 6.8 σ, µ =
H→ZZ→4l signal
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121.5 < m4l< 130.5
4 ee, 13 µe, 8 µµ events
HIG-13-002
Invariant Mass Spectrum ZZ→4l
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ZZ→4l - Mass and Spin
06.04.2014 16
Mass : 125.6 ± 0.4 (stat) ± 0.2 (sys)
Pseudo scalar and all spin 1 hypothesis excluded at >99%, spin 2 excluded at > 95% confidence level.
HIG-13-002
Spin Hypothesis Tests
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ZZ→4l - Production Mode
06.04.2014 17
Gluon fusion and VBF production rates as expected from SM.
HIG-13-002
Dijet
0/1-jet
best fit µ
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ZZ→4l - Width from Interference
06.04.2014 18
Interference cause ZZ event rate change of ~8% for m4l>2mZ for ΓH = ΓH SM
Obs. (exp.) @ 95% C.L. : ΓH < 4.2 (8.5) ΓH SM , ΓH < 17.4 (35.3) MeV
HIG-14-002
ΓH /ΓH SM
MELA Dgg m4l (GeV) Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
06.04.2014 19
H→γγ
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→γγ : Narrow peak - width determined by experimental resolution - over a large background.
Expect >500 H→γγ events in LHC run 1 data after final selection. Background in final analysis categories dominated by QCD di-photon
production – irreduceable. Analysis strategy : Improve S/B by categorizing events according to Higgs
production mode, Higgs kinematics and photon reconstruction performance.
H→γγ
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HIG-13-001
Calibration with > 3x109 π0 H→γγ Signal Model : σm ~1%
mγγ (GeV)
H→γγ
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Preliminary results from Moriond 2013 : Observed excess 3.2 σ , µ = 0.78+0.28
mH : 125.4±0.5(stat)±0.6(stat) Final results for LHC run 1 expected for summer conferences : Improved ECAL calibration, improved
detector simulation, refined categorization, optimized energy reconstruction and photon identification.
HIG-13-001
- 0.26
Channel compatibility for two alternative analysis
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
Properties measured in H→γγ
06.04.2014 22
Preliminary results : Acceptance of current analysis drops in region of largest sensitivity. Particular spin-2 model tested cannot be ruled out. Observed data is compatible with the SM with a χ2 p-value of 0.68.
|cos(𝜽𝜽CS)| fqq(%) *
HIG-13-016
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
Photon
Photon
Jet
Jet
H→γγ VBF Production
Jet
µggH, ttH
µ VB
F,VH
HIG-13-001
mγγ in γγ +2 jets category
06.04.2014 Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 23
VH→bb
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HIG-13-012
Mass Resolution H→bb
m(jj) (GeV)
Muon 0, pT : 161.8 GeV
Muon 1, pT : 27.3 GeV
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
VH→bb
06.04.2014 25
Very large backgrounds from SM processes.
Use associated production mode to enhance S/B.
HIG-13-012
Dijet mass cross-check S/B from BDT, all channels combined
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
VH→bb
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Six topologies considered. Significance around 2 sigma at 125 GeV. WH and ZH production modes consistent with SM expectations
HIG-13-012
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ττ
06.04.2014 27 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ττ
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H→ττ
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Observed significance 3.2 σ at mH =125 GeV
Couplings consistent with SM expectations.
HIG-13-004
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→ff Combination
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Combination of H→bb and H→ττ results.
Combined significance of 3.8 σ with a signal strength of 0.83±0.24.
HIG-13-033
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
ttH Analysis
06.04.2014 31
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
ttH - Combination
06.04.2014 32
HIG-12-025 HIG-13-015 HIG-13-019 HIG-13-020
Observed yields and distributions are compared to SM expectations.
Median expected combined limit : 1.8σ @ 95% C.L. in the absence of a signal, 2.9 assuming the presence of SM ttH.
Observed limit is 4.3σ @ 95% C.L. , reaching sensitivity to SM.
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→Zγ & H→γ*γ→µµγ
06.04.2014 33
Limits at ~10 times the SM cross section for H→Zγ and H→γ*γ→µµ. Only leptonic Z decays used.
Loop mediated, sensitive to BSM physics. Need 100 times more luminosity
⇒ HL-LHC.
HIG-14-003 HIG-13-006
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
H→µµ
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Lowes branching ratio. Efficiency for final state high.
Target for HL-LHC.
HIG-13-007
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
BSM Higgs Searches
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MSSM direct search : φ→µµ (w/o b-tag) neutral Higgs production in ττ channel.
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
HIG-13-021
NMSSM : additional gauge singlet wrt MSSM, one CP-even, one CP-odd. Most recent search h→a1a1→4µ
HIG-13-010
BSM Higgs Searches
36 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
Combined limit for Heavy Higgs and A (Type II) 2HDM. α an β determine the cross section for H and A production, the branching ratio Br(H → hh), Br(A → Zh) and Br(h → WW, ZZ, ττ, γγ).
Heavy Higgs from H→ZZ→2l2ν, assuming additional EWK singlet added to the SM.
HIG-13-025
06.04.2014
HIG-13-014
Precision Higgs Physics with HL-LHC
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High Luminosity LHC aims to deliver 3 ab-1
Precision Higgs physics, di-Higgs production, Higgs as a portal.
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
FTR-13-024
FTR-13-004
Study for 3 ab-1, A→Zh, φ→µµ, H→ZZ→4l
Upgrade studies for muon system, assuming increased forward acceptance for H→ZZ→4µ
Precision Higgs Physics with HL-LHC
06.04.2014 38
Upgrade R&D studies currently ongoing, aiming for a technical proposal later in 2014 or early 2015.
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
Track-Trigger
Forward Calorimeter & Precision Timing
Forward Muon System
Summary
06.04.2014 39
A wide range of Higgs production and decay modes have been analyzed with CMS data.
All measured signal strengths and properties are in agreement with expectation for a standard model Higgs boson. The mass measurements are consistent across channels.
Precision Higgs physics is opening the door to new territories.
Large amounts of luminosity are now needed to reveal the nature of the new boson and its role in fundamental physics.
Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
06.04.2014 40 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,
Does this answer all our questions ?