Combination of Standard Model Higgs boson searches and measurements of the properties of the new boson with a mass near 125 GeV

This is a condensed description with plots for the analysis CMS-HIG-12-045

Abstract

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Sensitivities

Plot Caption
The median expected 95% CL upper limits on the cross section ratio σ/σSM in the absence of a Higgs boson as a function of the SM Higgs boson mass in the range 110–1000 GeV (left) and 110–145 GeV (right), for the five Higgs boson decay channels. Here σSM denotes the cross section predicted for the SM Higgs boson. A channel showing values below unity (dotted red line) would be expected to be able to exclude a Higgs boson of that mass at 95% CL. The jagged structure in the limits for some channels results from the different event selection criteria employed in those channels for different Higgs boson mass sub-ranges.
The median expected p-value for observing an excess at mass mH in assumption that the SM Higgs boson with this mass exists, as a function of the SM Higgs boson mass in the range 110–1000 GeV (left) and 110–145 GeV (right). Expectations for subcombinations in five Higgs boson decay channels and the overall combination are shown.

Exclusion limits on the SM Higgs boson

Plot Caption
The CLs values for the SM Higgs boson hypothesis as a function of the Higgs boson mass. The observed values are shown by the solid line. The dashed line indicates the expected median of results for the background only hypothesis, while the green (dark) and yellow (light) bands indicate the ranges that are expected to contain 68% and 95% of all observed excursions from the median, respectively. The three horizontal lines on the CLs plot show confidence levels of 90%, 95%, and 99%, defined as (1–CLs).
The 95% CL upper limits on the cross section ratio σ/σSM for the SM Higgs boson hypothesis as function of the Higgs boson mass. The observed values are shown by the solid line. The dashed line indicates the expected median of results for the background only hypothesis, while the green (dark) and yellow (light) bands indicate the ranges that are expected to contain 68% and 95% of all observed excursions from the median, respectively.

Significance of the observed excess

Plot Caption
The observed local p-value p0 for 7-!TeV, 8-!TeV data, and their combination as a function of the SM Higgs boson mass. The dashed lines show the expected local p-value p0(mH), should a Higgs boson with a mass mH exist.
The observed local p-value p0 for five subcombinations by decay mode and the overall combination as a function of the SM Higgs boson mass. The dashed lines show the expected local p-value p0(mH), should a Higgs boson with a mass mH exist.
The observed local p-value p0 for γγ, ZZ and their combination as a function of the SM Higgs boson mass. The dashed lines show the expected local p-value p0(mH), should a Higgs boson with a mass mH exist.
The observed local p-value p0 for WW, bb, ττ and their combination as a function of the SM Higgs boson mass. The dashed lines show the expected local p-value p0(mH), should a Higgs boson with a mass mH exist.

Mass of the observed state

Plot Caption
(Left) 1D test statistics q(mH) scan vs hypothesized Higgs boson mass mH for the γγ and 4l final states separately and for their combination. In this combination, three independent signal strengths gg → H → γγ, VBF+VH → H → γγ, and H → ZZ → 4l are profiled together with all other nuisance parameters.
(Right) 2D 68% CL contours for a hypothesized Higgs boson mass mH and signal strength σ/σSM for the γγ and 4l, and their combination. In this combination, the relative signal strengths for the three final states are constrained by the expectations for the SM Higgs boson.
1D test statistics q(mH) scan vs hypothesized Higgs boson mass mH for the combination of the high resolution channels. 1D-scans of the test statistic q(mX) versus hypothesized boson mass mX for the combination of the γ&gamma and 4l final states. The solid line is obtained with all nuisance parameters profiled and, hence, includes both statistical and systematic uncertainties. The dashed line is obtained with all nuisance parameters fixed to their best-fit values and, hence, includes only statistical uncertainties. The crossings with the thick (thin) horizontal lines define the 68\% (95\%) CL interval for the measured mass.

Additional plots

Plot Caption
\ 1D test statistics –2 ln Q vs hypothesized Higgs boson mass mH for the diphoton final state. The solid line is obtained with all nuisance parameters profiled and, hence, includes both statistical and systematic uncertainties. The dashed line is obtained with all nuisance parameters fixed to their best-fit values and, hence, includes only statistical uncertainties. The crossings with the thick (thin) horizontal lines define the 68\% (95\%) CL interval for the measured mass.
\ 1D test statistics –2 ln Q vs hypothesized Higgs boson mass mH for the four-lepton final state. The solid line is obtained with all nuisance parameters profiled and, hence, includes both statistical and systematic uncertainties. The dashed line is obtained with all nuisance parameters fixed to their best-fit values and, hence, includes only statistical uncertainties. The crossings with the thick (thin) horizontal lines define the 68\% (95\%) CL interval for the measured mass.
2D test statistics –2 ln Q vs hypothesized Higgs boson mass mH and signal strength σ/σSM for the combination of the high resolution channels. The cross indicates the best-fit values. The solid, dashed, and dotted contours show the 68%, 95%, and 99.7% CL ranges, respectively. In this combination, the relative signal strengths for the various final states are constrained by the expectations for the SM Higgs boson.
2D test statistics –2 ln Q vs hypothesized Higgs boson mass mH and signal strength σ/σSM for the diphoton final state. The cross indicates the best-fit values. The solid, dashed, and dotted contours show the 68%, 95%, and 99.7% CL ranges, respectively. In this combination, the relative signal strengths for the various production modes are constrained by the expectations for the SM Higgs boson.
2D test statistics –2 ln Q vs hypothesized Higgs boson mass mH and signal strength σ/σSM for the four-lepton final state. The cross indicates the best-fit values. The solid, dashed, and dotted contours show the 68%, 95%, and 99.7% CL ranges, respectively.

Compatibility of the observed state with the SM Higgs boson hypothesis: signal strengths

Plot Caption
The observed best-fit signal strength μ̂ = σ/σSM as a function of the SM Higgs boson mass in the range 110–145 GeV. The bands correspond to the ±1σ uncertainties on the μ̂ values.
Values of μ̂ = σ/σSM for the combination (solid vertical line) and for contributing channels (points). The vertical band shows the overall μ̂ value 0.88 ± 0.21. The horizontal bars indicate the ±1σ uncertainties on the μ̂ values for individual channels; they include both statistical and systematic uncertainties.
Values of μ̂ = σ/σSM for the combination (solid vertical line) and for sub-combinations grouped by decay mode (points). The vertical band shows the overall μ̂ value 0.88 ± 0.21. The horizontal bars indicate the ±1σ uncertainties on the μ̂ values for individual channels; they include both statistical and systematic uncertainties.
Values of μ̂ = σ/σSM for the combination (solid vertical line) and for sub-combinations grouped by a signature enhancing specific production mechanisms (points). The vertical band shows the overall μ̂ value 0.88 ± 0.21. The horizontal bars indicate the ±1σ uncertainties on the μ̂ values for individual channels; they include both statistical and systematic uncertainties.
(Left plot) The 68% CL (solid lines) and (right plot) 68% CL (solid line) and 95% CL (dashed line) intervals for signal strength in the gluon-gluon-fusion-plus-ttH and in VBF-plus-VH production mechanisms: μgg+ttH and μ VBF+VH, respectively. The different colors show the results obtained by combining data from each of the five analayzed decay modes: γγ (green), WW (blue), ZZ(red), ττ (violet), bb (cyan). The crosses indicate the best-fit values. The diamond at (1,1) indicates the expected values for the SM Higgs boson.

Additional plots

Plot Caption
68% CL intervals of μ̂ = σ/σSM for the combination (vertical band) and for contributing channels (red lines) computed using the Feldman-Cousins construction.
The 68% CL (solid lines) intervals for signal strength in the gluon-gluon-fusion-plus-ttH and in VBF-plus-VH production mechanisms: μggH+ttH and μ VBF+VH, respectively using the Feldman-Cousins construction. The different colors show the results obtained by combining data from each of the five analayzed decay modes: γγ (green), WW (blue), ZZ(red), ττ (violet), bb (cyan). The crosses indicate the best-fit values. The diamond at (1,1) indicates the expected values for the SM Higgs boson.
Values of μ̂ = σ/σSM for the the individual channels. The horizontal bars indicate the ±1σ uncertainties on the μ̂ values for individual channels; they include both statistical and systematic uncertainties. The vertical dashed line indicates the prediction for a SM Higgs boson.
Values of μ̂ = σ/σSM for the sub-combinations by decay mode. The horizontal bars indicate the ±1σ uncertainties on the μ̂ values for individual channels; they include both statistical and systematic uncertainties. The vertical dashed line indicates the prediction for a SM Higgs boson.
Values of μ̂ = σ/σSM for the sub-combinations grouped by a signature enhancing specific production mechanisms. The horizontal bars indicate the ±1σ uncertainties on the μ̂ values for individual channels; they include both statistical and systematic uncertainties. The vertical dashed line indicates the prediction for a SM Higgs boson.

Numbers

The tables below contain the same information that is shown in figures 10a-10c of the HIG-12-045 PAS.

Channel μ̂ = σ/σSM
by decay mode value uncertainty
H → bb +1.075 -0.566/+0.593
H → ττ +0.875 -0.484/+0.508
H → γγ +1.564 -0.419/+0.460
H → WW +0.699 -0.232/+0.245
H → ZZ +0.807 -0.280/+0.349
by production tag and decay mode value uncertainty
H → bb (VH tag) +1.309 -0.601/+0.654
H → bb (ttH tag) -0.798 -1.840/+2.100
H → ττ (0/1 jet) +0.845 -0.657/+0.684
H → ττ (VBF tag) +0.819 -0.746/+0.824
H → ττ (VH tag) +0.861 -1.678/+1.924
H → γγ (untagged) +1.428 -0.457/+0.502
H → γγ (VBF tag) +2.256 -1.017/+1.286
H → WW (0/1 jet) +0.774 -0.247/+0.270
H → WW (VBF tag) -0.046 -0.552/+0.737
H → WW (VH tag) -0.305 -1.943/+2.223
H → ZZ +0.807 -0.280/+0.349
by production tag value uncertainty
Untagged +0.891 -0.186/+0.208
VBF tag +0.915 -0.477/+0.526
VH tag +1.135 -0.547/+0.597
ttH tag -0.798 -1.840/+2.100

Tests of the Couplings

Test of Fermion and Vector Boson Couplings

Plot Caption
2D test statistics q(κV, κF) scan.
2D test statistics q(κV, κF) scan, including individual channels.
1D test statistics q(κV) scan, profiling κF.
1D test statistics q(κF) scan, profiling κV.
1D test statistics q(κV) scan, if κF is fixed to the SM value.
1D test statistics q(κF) scan, if κV is fixed to the SM value.

Test of Custodial Symmetry

Using only untagged WW and ZZ events and assuming SM couplings to fermions

Plot Caption
1D test statistics q(λWZ) scan vs the coupling modifier ratio λWZ, profiling the coupling modifier κZ and all other nuisances. The coupling to fermions is taken to be the SM one (κF = 1).
2D test statistics q(λWZ, κZ) scan, profiling all other nuisances.

Using all channels, and without assumption on the couplings to fermions (except their universality)

Plot Caption
1D test statistics q(λWZ) scan vs the coupling modifier ratio λWZ, profiling the coupling modifiers κZ and κF and all other nuisances.
2D test statistics q(λWZ, κZ) scan, profiling the coupling modifier to fermions κF and all other nuisances.
2D test statistics q(λWZ, κF) scan, profiling the coupling modifier to the Z boson κZ and all other nuisances.
2D test statistics q(κZ, κF) scan, profiling the modifier to the ratio of W and Z couplings λWZ and all other nuisances.

Test of Fermion Universality

Up-type vs Down-type Fermions

Plot Caption
1D test statistics q(λdu) scan vs the coupling modifier ratio λdu, profiling the coupling modifiers κu and κV and all other nuisances. κu and κV are always taken to be positive.
2D test statistics q(λdu, κu) scan, profiling the coupling modifier to vector bosons κV and all other nuisances. κu and κV are always taken to be positive.
2D test statistics q(λdu, κV) scan, profiling the coupling modifier to the up-type fermions κu and all other nuisances. κu and κV are always taken to be positive.
2D test statistics q(κV, κu) scan, profiling the modifier to the ratio of up-type and down-type couplings λdu and all other nuisances.

Leptons vs Quarks

Plot Caption
1D test statistics q(λlq) scan vs the coupling modifier ratio λlq, profiling the coupling modifiers κq and κV and all other nuisances. κq and κV are always taken to be positive.
2D test statistics q(λlq, κq) scan, profiling the coupling modifier to vector bosons κV and all other nuisances. κq and κV are always taken to be positive.
2D test statistics q(λlq, κV) scan, profiling the coupling modifier to the quarks κq and all other nuisances. κq and κV are always taken to be positive.
2D test statistics q(κV, κq) scan, profiling the modifier to the ratio of lepton to quark couplings λlq and all other nuisances.

Search for Beyond Standard Model Physics in Loops

Plot Caption
2D test statistics q(κg, κγ) scan.
1D test statistics q(κg) scan, profiling the modifier to the effective coupling to photons κγ.
1D test statistics q(κγ) scan, profiling the modifier to the effective coupling to gluons κg.

Search for Beyond Standard Model Physics in Loops and Decays

Plot Caption
1D test statistics q(BRBSM) scan, profiling the modifier to the effective coupling to photons and gluons κγ, κg.
2D test statistics q(κg, BRBSM) scan, profiling the modifier to the effective coupling to photons κγ.
2D test statistics q(κg, κγ) scan, profiling the branching ratio to BSM decays BRBSM.

Generic search for deviations in the couplings

The search is performed with six independent coupling modifiers κV, κb, κτ, κt, κg, κγ
Plot Caption
1D test statistics q(κV) scan, profiling the other five coupling modifiers.
1D test statistics q(κb) scan, profiling the other five coupling modifiers.
1D test statistics q(κτ) scan, profiling the other five coupling modifiers.
1D test statistics q(κt) scan, profiling the other five coupling modifiers.
1D test statistics q(κγ) scan, profiling the other five coupling modifiers.
1D test statistics q(κg) scan, profiling the other five coupling modifiers.
2D test statistics q(κV, κγ) scan, profiling the other four coupling modifiers.
2D test statistics q(κg, κb) scan, profiling the other four coupling modifiers.
2D test statistics q(κb, κτ) scan, profiling the other four coupling modifiers.
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Topic revision: r13 - 2012-11-23 - GiovanniPetrucciani
 
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