Search for Standard Model Higgs Boson Production in Association with W Boson at CDF with 695pb^-1

1. Authors
2. Abstract
3. Documentation
4. Tables
5. Figures
    5.1 Jet Multiplicity
    5.2 Dijet Mass Distribution
    5.3 Acceptance
    5.4 Sensitivity
    5.5 Expected Limit at 95% C.L.(Comparison)
    5.6 Likelihood
    5.7 Observed Limit (Result)
    5.8 Pseudo Experiment(Cross Check)

Authors

Yoshiaki Kusakabe, Kunitaka Kondo	(Waseda)
Tatsuya Masubuchi, Yoshio Ishizawa, Shinhong Kim	(University of Tsukuba)
Anyes Taffard	(University of Illinois Urbana-champaign)
Michael McFarlane, Nielsen Jason, Weiming Yao	(LBNL)

Abstract

We present a search for standard model higgs boson production in assocation with a W boson. This search uses data corresponding to an integrated luminosity of 695pb^-1. We require one SECVTX tagged jet that passes the neural network b-tagging selection and double SECVTX tagged jets in the W+2jet events. The number of tagged events and the dijet mass distributions are consistent with the standard model expectations. We set an upper limit on the WH procudtion cross section times branching ratio as

sigma(pp -> WH)BR(H->bb) < 4.0 - 2.0 (pb)

Higgs masses from 110GeV/c² to 150GeV/c² (95% C.L.)

Documentation

CDF-8240 ...Public Note

Related Analysis

1. tt production cross section measurement in SecVtx b-tagged lepton+jets event
2. tt production cross section measurement using the Neural Network b-tagger
3. Neural Network b-tagging
4. Search for New Particles Decaying into bb and Produced in Association with W Boson(previous analysis with 319pb^-1)

Tables

Notice! Tables used in the final result are exactly 1-btagging w/ NN tagging and double tag

Background estimate

gif,eps Background summary table for at least one b-tagged event.(w/o NN tagging)	gif,eps Background summary table for at least one b-tagged event w/ NN tagging.
gif,eps Background summary table for exactly 1 b-tagged event.(w/o NN tagging)	used in the final result gif,eps Background summary table for exactly 1 b-tagged event w/ NN tagging.
used in the final result gif,eps Background summary table for double tagged events.(w/o NN tagging)

Systematic Uncertainties

All of the b-tagging strategies considered in this analysis

gif, eps Systematic uncertainties for each b-tagging condition and each source of the uncertainty. (All of the b-tagging strategies used to find the best sensitivities are shown.)

Only the b-tagging strategies used in the final result

gif, eps Systematic uncertainties of each source of the uncertainty for =1tag w/ NN tag and double tagging condition respactively.(Only the numbers used in the final result)

Figures

Notice! Plots used in the final result are exactly 1-btagging w/ NN tagging and double tag
To open eps file correctly, please turn off "Antialias" in ghost view option

Jet Multiplicity

stage	>=1tag	>=1tag w/ NN tag	used in the final result =1tag w/ NN tag	used in the final result >=2tag
Plot
Links	gif eps	gif eps	gif eps	gif eps
Jet Multiplicity distributions for each b-tag stage. Red hashed boxes are the total background uncertainties. Stages of =1tag w/ NN tag and >=2tag are used in final result.

Dijet Mass Distribution

stage	>=1tag	>=1tag w/ NN tag	used in the final result =1tag w/ NN tag	used in the final result >=2tag
Plot w/ signal line	gif eps	gif eps	gif eps	gif eps
Plot w/ signal histogram on background	gif eps	gif eps	gif eps	gif eps
Other Kinematics	>=1 tag	>=1 tag w/ NN tag	=1 tag w/ NN tag	>=2 tag
Dijet mass distributions for each b-tag stage. Red hashed boxes are totab background uncertainties. Stages of =1tag w/ NN tag and >=2tag are used in the final result. Other kinematics such as jet Et, Eta, Phi, lepton kinematics are found in the link to other kinematics above for each stage.

Acceptance

All of the b-tagging strategies considered in this analysis gif eps	Only b-tagging strategies related with the final result gif eps
Higgs signal acceptance as a funtion of higgs mass for various b-tagging strategies. Neural Network b-tagging retains about 90% of WH signal.

Sensitivity

gif eps

Sensitivities for various b-tagging strategies as a function of higgs mass. This plot shows that the best sensitivity is obtained by combining =1tag w/ NN tag and >=2 tag.

Expected Limit at 95% Confidence Level(Comparison)

Normal scale	Log scale
gif eps	gif eps
Expected limit at 95% C.L. for a various b-tagging strategies. The expected limit obtained in the previous analysis with 319pb^-1(using >=1 tag events) is also shown to see how much improvement we get in this analysis. The best expected limit is obtained by combining =1tag w/ NN tag and >=2 tag, which is corresponding to the sensitivity plots above.

Likelihood

=1tag w/ NN tag	double tag	combined

gif eps	gif eps	gif eps
Likelihood function as a function of cross section times Branching ratio obtained by fitting the dijet mass distributions of =1tag w/ NN tag and >=2 tag events at mH=115GeV/c². Red arrow shows the 95% C.L. upper limit. The combined likelihood gives the final result.

Observed Limit at 95% C.L.(Result)


gif eps	gif eps
Observed limit at 95% C.L. as a function of higgs mass obtained from the combined likekihood of exactly 1 tag w/ NN tag and double tag. Observed limit in the previous analysis with 319pb^-1 is also shown.

Pseudo Experiment(Cross Check)

gif eps gif eps gif eps

Number of pseudo experiments and observed limit to check if the observed limit is statistically reasonable for each higgs mass considered in this analysis.

Contents