Search for the H → b¯b decay mode of the Standard Model Higgs boson in associated production with a vector boson in proton-proton collisions at √s = 8 TeV with the ATLAS experiment

Abstract

In this thesis, a search for the H→b¯b decay mode of the Standard Model Higgs boson in associated production with a vector boson is presented. The search is based on the entire data-set recorded by the ATLAS experiment in 2012 amounting to 20.3fb^-1 of data. A novel search strategy based on a machine learning approach using boosted decision trees and a variable set constructed from Lorentz invariant quantities is introduced.<br /> No significant excess above the Standard Model background expectation is observed. For a Higgs boson mass of m_H=125GeV, the expected upper limit on the Higgs boson production cross section assuming the absence of signal is 2.06×σ_SM, while the observed limit is 3.15×σ_SM. This excess corresponds to a local significance of 1.1 standard deviations. The ratio of the measured signal strength to the Standard Model expectation is μ=1.40±0.95.