Search for the Standard Model Higgs Boson in Associated Production with W Boson at the Tevatron.

Abstract

A search for the Standard Model Higgs boson in proton-antiproton collisions with center-of-mass energy 1.96 TeV at the Tevatron is presented in this dissertation. The process of interest is the associated production of W boson and Higgs boson, with the W boson decaying leptonically and the Higgs boson decaying into a pair of bottom quarks. The dataset in the analysis is accumulated by the D0 detector from April 2002 to April 2008 and corresponding to an integrated luminosity of 2.7 fb$^{-1}$. The events are reconstructed and selected following the criteria of an isolated lepton, missing transverse energy and two jets. The D0 Neural Network b-jet identification algorithm is further used to discriminate b jets from light jets. A multivariate analysis combining Matrix Element and Neural Network methods is explored to improve the Higgs boson signal significance. No evidence of the Higgs boson is observed in this analysis. In consequence, an observed (expected) limit on the ratio of $sigma$ (ppbar $rightarrow$ WH) $times$ Br (H $rightarrow$ bbbar) to the Standard Model prediction is set to be 6.7 (6.4) at $95%$ $C.L.$ for the Higgs boson with a mass of 115 GeV.