Search for the standard model Higgs boson in association with a W boson at D0.

Abstract

I present a search for the standard model Higgs boson, H, produced in association with a W boson in data events containing a charged lepton (electron or muon), missing energy, and two or three jets. The data analysed correspond to 9.7 fb-1 of integrated luminosity collected at a center-of-momentum energy of √s = 1.96 TeV with the D0 detector at the Fermilab Tevatron p$\bar{p}$ collider. This search uses algorithms to identify the signature of bottom quark production and multivariate techniques to improve the purity of H → b$\bar{b}$ production. We validate our methodology by measuring WZ and ZZ production with Z → b$\bar{b}$ and find production rates consistent with the standard model prediction. For a Higgs boson mass of 125 GeV, we determine a 95% C.L. upper limit on the production of a standard model Higgs boson of 4.8 times the standard model Higgs boson production cross section, while the expected limit is 4.7 times the standard model production cross section. I also present a novel method for improving the energy resolution for charged particles within hadronic signatures. This is achieved by replacing the calorimeter energy measurement for charged particles within a hadronic signature with the tracking momentum measurement. This technique leads to a ~ 20% improvement in the jet energy resolution, which yields a ~ 7% improvement in the reconstructed dijet mass width for H → b$\bar{b}$ events. The improved energy calculation leads to a ~ 5% improvement in our expected 95% C.L. upper limit on the Higgs boson production cross section.