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Combination of Higgs Searches

This is a condensed description with plots for the analysis LINK TO CDS

Abstract

The overall combination is presented of eight standard model (SM) Higgs boson searches performed by the CMS Collaboration using the following Higgs boson decay signatures: H → γγ, H → ττ, H → bb, H → WW → 2l2ν, H → ZZ → 4l, H → ZZ → 2l2τ, H → ZZ → 2l2ν, and H → ZZ → 2l2q. Depending on the analysis, the amount of data used corresponds to 1.1-1.7 fb−1 of integrated luminosity. The SM Higgs boson is excluded at 95% C.L. in three mass ranges 145-216, 226-288, and 310-400 GeV/c². The expected exclusion in the absence of a signal is 130-440 GeV/c². The largest excursion of the observed data from the expected has a probability of 0.4 after taking into account the look-elsewhere effect. At 90% C.L., we exclude the SM Higgs boson in the continuous mass range from 144-440 GeV/c². The reported limits were obtained using the modified frequentist construction known as the CLs method.

Plots

Figure setSorted ascending Description Variants
The CLs value for the standard model Higgs hypothesis as a function of the Higgs boson mass in the range 110-600 GeV/c².
The observed values are shown by a solid line. The dashed black line indicates the median expected CLs value for the background-only hypothesis, while the green/yellow bands indicate the ranges that are expected to contain 68%/95% of all observed limit excursions from the median. The three red horizontal lines show confidence levels of 90%, 95%, and 99% defined as (1 - CLs).
linear x (png, eps, pdf)
log x (png, eps, pdf)
low mass (png, eps, pdf)
The combined 95% C.L. upper limits on the signal strength modifier μ = σ/σSM, as a function of the SM Higgs boson mass in the range 110-600 GeV/c².
The observed limits are shown by the solid symbols and the black line. The dashed line indicates the median expected limit on m for the background-only hypothesis, while the green/yellow bands indicate the ranges that are expected to contain 68%/95% of all observed limit excursions from the median.
linear x (png, eps, pdf)
log x (png, eps, pdf)
low mass (png, eps, pdf)
The combined 95% C.L. upper limits on the signal strength modifier μ = σ/σSM, as a function of the SM Higgs boson mass in the range 110-600 GeV/c².
The observed limits are shown by the solid symbols and the black line. The dashed line indicates the median expected limit on m for the background-only hypothesis, while the green/yellow bands indicate the ranges that are expected to contain 68%/95% of all observed limit excursions from the median. The mass ranges excluded by LEP, by Tevatron and by this result are shown as hatched areas.
linear x (png, eps, pdf)
log x (png, eps, pdf)
low mass (png, eps, pdf)
The combined 95% C.L. upper limits on the signal strength modifier μ = σ/σSM, as a function of the SM Higgs boson mass in the range 110-600 GeV/c².
The observed limits are shown by the solid symbols and the black line. The dashed line indicates the median expected limit on m for the background-only hypothesis, while the green/yellow bands indicate the ranges that are expected to contain 68%/95% of all observed limit excursions from the median. The Tevatron observed and expected limits are also shown.
png, pdf
The 95% C.L. upper limits on the signal strength modifier μ = σ/σSM as a function of the SM Higgs boson mass in the range 110-600 GeV/c² for the eight major analyses and their combination.
The limits are obtained with the CLs method. The solid lines show the observed limits, while the dashed lines indicate the median expected assuming the background-only hypothesis.
linear x (png, eps, pdf)
log x (png, eps, pdf)
low mass (png, eps, pdf)
The observed 95% C.L. upper limits on the signal strength modifier μ = σ/σSM as a function of the SM Higgs boson mass in the range 110-600 GeV/c² for the eight major analyses and their combination.
The limits are obtained with the CLs method.
linear x (png, eps, pdf)
log x (png, eps, pdf)
low mass (png, eps, pdf)
The local p-values (top) and observed best-fit signal strength μ̂ = σ/σSM (bottom) vs Higgs boson mass.
The p-value is an estimated probability of upward background fluctuations as high or higher than the excesses observed in data. After taking into account the look-elsewhere effect (see text), the probability to see an excess at least as large as the one observed in data is ∼0.4. The μ̂ value indicates by what factor the SM Higgs cross section would have to be rescaled to best match the observed data.
linear y (png, eps, pdf)
log y (png, eps, pdf)
The overall combined local p-values (solid black line) and contributions of individual channels entering the combination vs. Higgs boson mass.
The p-valuee is an estimated probability of upward background fluctuation as high or higher than the excesses observed in data. After taking into account the look-elsewhere effect (see text), the probability to see an excess at least as large as the one observed in data is ∼0.4.
linear x (png, eps, pdf)
log x (png, eps, pdf)
low mass (png, eps, pdf)

Tables

The following tables are also available as individual files in text format:

-- AndreyKorytov - 23-Aug-2011

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Topic revision: r1 - 2011-08-23 - AndreyKorytov
 
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