Combined Upper Limit on Standard Model Higgs Boson Production at CDF for Summer 2008

T. Junk1), N. Krumnack2), W.-M. Yao3)

1)FNAL,2)Baylor University,3)LBNL

For the CDF Higgs Working Group


Contents

Abstract
Documentation
NNLO Cross Section Table
Bayesian Framework
Posterior Probability
Expected limits from Pseudo Experiments
Combined Results with 3.0 fb-1(Summer 2008)
Summary Plots sorted by s/b
Projections

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Abstract

A combination of several searches for Standard Model Higgs boson production at CDF using a data sample up to 1.9 to 3.0 fb-1 of integrated luminosity is performed. The channels considered are WH-> lνbb, ZH->ννbb, ZH->l-l+bb, gg -> H -> W+W-, and a new search for VH->&tau-;&tau++2jet for the first time. We have calculated combined upper limits on the ratio of Higgs boson cross section times the branching ratio to its Standard Model prediction(R95) for Higgs boson masses between 100 and 200 GeV/c2. The results are in good agreement with the expectations obtained from background-only pseudo-experiments. The 95% CL upper limits observed (expected) are factors of 4.2 (3.6) and 1.5 (1.7) higher than the Standard Model production cross sections for Higgs boson masses of 115 and 160 GeV/c2, respectively.

Documentation

Each channel


NNLO Cross Section

Cross Section is obtained from TeV4LHC Higgs working group, with the following modifications: The branching ratios are obtained from John Conway's Calculation with HDECAY

Bayesian Framework


Combination Results with 3.0 fb-1 (Summer 2008)

The combined upper limit as a function of the Higgs boson mass
between 100 and 200 GeV/c2
Solid black: observed limit/SM; Dashed black: median expected limit/SM
Colored bands: +-1, 2 sigma distributions around median expected limit.
The combined upper limit as a function of the Higgs boson mass
between 100 and 200 GeV/c2.
Solid lines indicate the observed upper limit for each channel and
combined result (dark red).
Dashed lines indicate the median expected upper limit for each channel and
combined result (dark red).
 
The summary table of observed limit and expected limit
between 100 and 200 GeV/c2.

Posterior Probability

Posterior densities for all channels combined for Higgs boson mass between 100 and 200 GeV/c2.
Red arrows indicate the 95% credibility upper limits.

Expected Limits with Pseudo-experiments



Events Ranked by s/b

Events in all search channels, sorted by the s/b in the bins in which they are found. Signal and background totals are shown, not stacked. This plot is shown for mH=115 GeV/c2 Cumulative distributions of background, data and signal+background. The s/b distribution is integrated from the high s/b side downwards. This plot is shown for mH=115 GeV/c2
Events in all search channels, sorted by the s/b in the bins in which they are found. Signal and background totals are shown, not stacked. This plot is shown for mH=160 GeV/c2 Cumulative distributions of background, data and signal+background. The s/b distribution is integrated from the high s/b side downwards. This plot is shown for mH=160 GeV/c2

Projections

Achieved and projected median expected upper limits on the SM Higgs boson cross section, by date. The solid lines are 1/sqrt(L) projections. The top of the yellow band corresponds to the Summer 2007 performance expected limit divided by 1.5, and the bottom of the yellow band corresponds to the Summer 2007 performance expected limit divided by 2.25. This plot is shown for mH=115 GeV/c2 Achieved and projected median expected upper limits on the SM Higgs boson cross section, by date. The solid lines are 1/sqrt(L) projections. The top of the yellow band corresponds to the Summer 2007 performance expected limit divided by 1.5, and the bottom of the yellow band corresponds to the Summer 2007 performance expected limit divided by 2.25. This plot is shown for mH=160 GeV/c2

August 26, CDF Higgs Working Group