Combined Upper Limit on Standard Model Higgs Boson Production at CDF for Summer 2007

Pedro Fernaldez1), Tom Junk6), Nils Krumnack2), Tatsuya Masubuchi3),
Jason Nielsen4), Anyes Taffard5), Weiming Yao1)

1)LBNL,2)Baylor University,3)University of Tsukuba,
4)UC Santa Cruz,5)UC Irvine,6)UIUC

For Higgs Working Group

Contents

Abstract
Documentation
Systematic Table
NNLO Cross Section Table
Bayesian Framework
Posterior Probability
Pseudo Experiment
Combined Result
Combined Result with 1 fb-1

Abstract

A combination of several searches for Standard Model Higgs boson production at CDF using a data sample up to 1 to 1.9fb-1 of integrated luminosity is performed. The channels considered are WH-> lνbb, ZH->ννbb, ZH->l-l+bb and gg -> H -> W+W-. All the results are available for 1.0fb-1. WH-> lνbb and H -> W+W- analysis is updated using 1.7 and 1.9fb-1, respectively. This time WH analysis is improved using double tags and Neural Network technique as well as increasing integrated luminosity and H -> W+W- Matrix Element analysis uses 1.9fb-1. 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 110 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 9.2 (6.6) and 1.8 (3.4) higher than the Standard Model production cross sections for Higgs boson masses of 115 and 160,GeV/c2, respectively.

Documentation

Each channel

Systematics
Systematic uncertainties. Positive value means 100% correlation between channels and
negative value means uncorrelated between channels

NNLO Cross Section
NNLO cross section and branching ratio.
Cross Section is refereed from TeV4LHC Higgs working group
Branching ratio is refereed from John Conway's Calculation with HDECAY

Bayesian Framework

Posterior Probability
Posterior densities for all channels combined for Higgs boson mass between 110 and 200 GeV/c2.
Where red arrows indicate the 95% credibility upper limit.

Pseudo Experiment
The distributions of upper limits from pseudo experiments for Higgs boson mass between 110 and 200 GeV/c2.
Where red arrows indicate the observed 95% upper limit from data.

Combination Result with 1.9fb-1
The combined upper limit as a function of Higgs boson mass
between 110 and 200 GeV/c2.
Solid lines mean observed upper limit for each channel and
combined result (black).
Dash lines mean expected upper limit for each channel and
combined result (black).		 The summary table of observed limit and expected limit
between 110 and 200 GeV/c2.

Combination Result with 1fb-1
The combined upper limit as a function of Higgs boson mass
between 110 and 200 GeV/c2.
Solid lines mean observed upper limit for each channel and
combined result (black).
Dash lines mean expected upper limit for each channel and
combined result (black).		 The summary table of observed limit and expected limit
between 110 and 200 GeV/c2.

Posterior Probability with 1fb-1
Posterior densities for all channels combined for Higgs boson mass between 110 and 200 GeV/c2.
Where red arrows indicate the 95% credibility upper limit.

Pseudo Experiment with 1fb-1
The distributions of upper limits from pseudo experiments for Higgs boson mass between 110 and 200 GeV/c2.
Where red arrows indicate the observed 95% upper limit from data.

Systematics with 1fb-1
Systematic uncertainties. Positive value means 100% correlation between channels and
negative value means uncorrelated between channels
Last modified: Mon Sep 3 21:19:12 JST 2007