higgs property measurements with the compact muon...
TRANSCRIPT
Higgs Candidate Property Measurements with the
Compact Muon Solenoid
Andrew Whitbeck*
for the CMS Collaboration
*Johns Hopkins University
Rencontres de Moriond QCD, La Thuile, ItalyMarch 14, 2013
Overview
• Higgs Candidate
– >7σ @ 126 GeV
– evidence observed in 5 channels
• Start constraining properties
– Spin-Parity (24.7/fb)
• ZZ, WW
– Mass measurement (17.3/fb)
– Coupling fits (17.3/fb)
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November 2012
Spin-Parity
• Using kinematic distributions to distinguish different signal models
– Probe different amplitude structures
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JP Description
0- CP-odd scalar
0h+ CP-even w/ HD operators
1+ Axial-vector
1- Vector
2m+ (gg) gg -> min coupling grav
2m+(qq) qq->min coupling grav
• Test compatibility of data with distinct models (Neyman-Pearson hypothesis testing)
• Null Hypothesis always SM Higgs
models and MC event generator used described in arXiv:1208.4018
Spin-Parity(ZZ)
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• First results on 0- by CMS PRL. 110, 081803 (2013)
•PX taken from JHUGen1,2 (signal) and MCFM3 (qqZZ) LO ME Calculations• cross-check with analytical1,2,4 andmadgraph5
1arXiv:1208.4018, 2arXiv:1001.3396, 3arXiv:1105.0020, 4arXiv:1211.1959, 5arXiv:1210.0896
1-
qq2m+
1+
DJP Distributions
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0h+
Dbkg>.5
gg2m+
0-
Spin-Parity (WW)• mll-mT plane also used to test gg->2m+ hypotheses
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Mll
[Ge
V]
Mll
[Ge
V]
Mll
[Ge
V]
MT [GeV] MT [GeV]
MT [GeV]
Higgs Properties - Moriond QCD
Spin-Parity Results
73/14/2013
0-
1-
qq2m+
1+
0h+
gg->2m+->WW
gg->2m+->ZZ
fitted μ separation
JP production comment expect (μ=1) obs. 0+ Obs. JP CLs
0- gg→X Pseudoscalar 2.6σ (2.8σ) 0.5σ 3.3σ 0.16%
0h+ gg→X Higher dim operators 1.7σ (1.8σ) 0.0σ 1.7σ 8.1%
2m+ gg→X Minimal couplings 1.8σ (1.9σ) 0.8σ 2.7σ 1.5%
2m+ qq→X Minimal couplings 1.7σ (1.9σ) 1.8σ 4.0σ <0.1%
1- qq→X Exotic vector 2.8σ (3.1σ) 1.4σ >4.0σ <0.1%
1+ qq→X Exotic axial-vector 2.3σ (2.6σ) 1.7σ >4.0σ <0.1%
Spin-Parity Results
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fitted μ separation
JP production comment expect (μ=1) obs. 0+ Obs. JP CLs
2m+ gg→X Minimal couplings 1.8σ (2.4σ) 0.5σ 1.3σ 14%
HZZ
HWW
CLs = P(q>q0|alt)/P(q>q0|SMH)
Mixed Parity (ZZ)
fa3 = |A3|2/(|A1|2+|A3|2)
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fa3 = 0.00 +0.23-0.00
fa3<0.58 @ 95% C.L.
μ profiled
ExpectedObserved
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Combined Results
Mass Measurement
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• Combined mass using HZZ and Hγγ
•Resolutions of 1-2%• signal strength for Hγγ, Hγγ +2j, and HZZ profiled(model independent)
•Results consistent when relative yields are fixed to SM
mH = 125.8 +/- 0.4 (stat) +/- 0.4 (syst) GeV
Coupling Compatibility
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N(xx→H→yy) ~ σ(xx→H) ∙ BR(H→yy) ~ Γxx ∙Γyy/Γtot
• 8 parameters describing yields in 5 channels
– ΓWW , ΓZZ , Γγγ , Γbb , Γgg , Γtt , Γττ , Γtot
• Test compatibility through variations w/ respect to SM using scaling factors1
– Deviations from κi =1 imply new physics
e.g.
1arXiv:1209.0040
Signal Strength
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σ/ σSM = 0.88 +/- 0.21
ggH VBFH VH ttH
H→γγ
H→ZZ
H→WW
H→ττ
H→bb
Rv-Rf
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• Best fit signal strength in VBF+VH production vs. ggH+ttH production
HZZ 4l H
μggH+ttHμggH+ttH
μq
qH
+VH
μq
qH
+VH
Hidden BSM Physics
• New physics can appear in loop diagrams:
– Effects Γgg, Γγγ and Γtot
• Invisible decay effect total width
– Scale total width:
• BRBSM = ΓBSM/Γtot
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[0.00,0.62] @ 95% CL
Custodial Symmetry
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λWZ = κW/ κZ
Assume λWZ =1 from now on
κZ profiledAll channelsκZ ,κf profiled
[0.67,1.55] @ 95% CL[0.57,1.65] @ 95% CL
Fermion Universality
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• 2-Higgs-Doublet models can affect
– up-type, down-type fermions differently
– leptons, quarks differently
[0.00,2.11] @ 95% CL [0.45,1.66] @ 95% CL
κV and κq (κu) profiled
Couplings (κv,κf)
Sign of κf driven by Hγγ: |ακV+βκf|2
κV=1: [0.40,1.12] @ 95% CL
κf=1: [0.78,1.19] @ 95% CL
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κf constrained >0
Conclusions
• Data consistent with – Custodial symmetry– Fermion universality tests– Fermionic and bosonic couplings
expected from SM Higgs
• Data disfavors all alternative models tested thus far at 2σ CL except 0h+
(0-,1+,1-,gg->2m+,qq->2m+)
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mH = 125.8 +/- 0.4 (stat) +/- 0.4 (syst) GeV
σ/ σSM = .88 +/- 0.21
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Thanks!For more information:
CMS Higgs Combination PAS: CMS-PAS-HIG-12-045CMS Higgs ZZ4l PAS: CMS-PAS-HIG-13-002
CMS Higgs WW(2l2ν) PAS: CMS-PAS-HIG-13-003CMS Hbb PAS: CMS-PAS-HIG-12-044 CMS Hγγ PAS: CMS-PAS-HIG-13-001CMS Hττ PAS: CMS-PAS-HIG-12-004
BACKUP
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References:ZZ Kinematics
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- Y. Gao et al., “Spin determination of single-produced resonances at hadron colliders”, Phys. Rev. D 81 (2010) 075022, doi:10.1103/PhysRevD.81.075022, arXiv:1001.3396.-S. Bolognesi et al., “On the spin and parity of a single-produced resonance at the LHC”, Phys. Rev. D 86 (2012) 095031, doi:10.1103/PhysRevD.86.095031, arXiv:1208.4018.- Y. Chen, N. Tran, and R. Vega-Morales, “Scrutinizing the Higgs Signal and Background in the 2e2m Golden Channel”, arXiv:1211.1959.- J. M. Campbell, R. Ellis, and C. Williams, “Vector boson pair production at the LHC”, JHEP 07 (2011) 018, doi:10.1007/JHEP07(2011)018, arXiv:1105.0020.-P. Avery et al., “Precision studies of the Higgs boson decay channel H \to ZZ* \to 4l with MEKD”, accepted by Phys.Rev.D. (2012) arXiv:1210.0896.
ZZ Measurements
• Loose selection to maximize signal efficiency
– Di-jet tagged and non di-jet tagged
• Sensitivity to VBF and VH/ttHproduction
– Full description of event kinematics
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For more details see previous talk on di-boson analyses: C. Ochando
ZZ Event Categories
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Sen
siti
ve t
o P
rod
uct
ion
Me
chan
ism
Sen
sitive to
Higgs K
ine
matics
di-jet tagged
No di-jet
For more details see previous talk on di-boson analyses: C. Ochando
ZZ Signal Strength
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σ/ σSM = 0.91 +0.30 -0.24 at mH=125.8 GeV
For more details see previous talk on di-boson analyses: C. Ochando
Spin-0 Amplitude
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• Most general spin-0 amplitude for X→VV
• a1 : SM Higgs (0m+)
• a2: CP-even scalar w/ HD operators (0h+)
• Contributes to Hγγ also
• a3: pseudoscalar (0-)
• Small correction from a3 in SM Higgs
Spin-1 Amplitude
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• Most general spin-1 amplitude for X→VV
• b1 : axial-vector (1+)
• B2: vector (1-)
Spin-2 Amplitude
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• Most general spin-2 amplitude for X→VV
• Minimal coupling graviton made of all terms proportional to Λ0 (g1=g5=1)
Hypothesis Testing (ZZ)
Testing data against large numbers of pseudo-experiments
fixing μ to SM expectation
fitting μ on data
Expected separation takenfrom average type 1 and type 2 errors
Observations interpretedby p-value of either distribution
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Hypothesis Testing (ZZ)
• Events are described by 2D histograms
Dbkg vs D0-
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3/14/2013
qqZZ
SM Higgs
0-
Hypothesis Testing (ZZ)
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• Large deviations from 0+ and spin-1 models
– Driven by excess of events in tails of mass distributions• Mass distributions differ considerably for spin-0 and spin-1 models
– Some events were already present in ICHEP 2012 dataset
Kinematics Distributions
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• Mz1 distributions are more distinct for different spin-1 and spin-2 models
– spin-1 and spin-2 KDs will provide more weight to events in tails of these distributions
KD Correlations
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• Strong correlation between non-scalar KDs
WW Analysis
• 6 event categories
– (0-jet, 1-jet) x (ee,mumu,emu)
• 2D shape-based analysis (mT vs mll)
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For more details see previous talk on di-boson analyses: C. Ochando
Combined Mass
• Combining 2 high resolution channels (ZZ, γγ)
• Branching ratios fixed to SM Higgs expectations
• Signal strength for Hγγ, Hγγ +2j, and HZZ treated as nuisances
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mH = 125.8 +/- 0.4 (stat) +/- 0.4 (syst) GeV
Signal Strength
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σ/ σSM = 0.88 +/- 0.21All Channels consistent with SM All event classes consistent with SM
Signal Strength
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• Best fit signal strength in VBF+VH prod. vs. ggH+ttH prod.
– mH = 125.8 GeV
– Curves represent 68% CL contours
Coupling (κv,κf)
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• κf vs κv by channel
– parameters constrained to be positive
• All channels consistent with SM Higgs expectation
Coupling Measurements
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κb κτ
κg
κV
κt
κγ