A Sensitivity Study for Higgs Boson Production in Vector Boson Fusion in the H → ττ → lh + 3v Final State with ATLAS

For a hypothetical Higgs boson mass between 114.4 GeV and about 135 GeV the production by Vector Boson Fusion and the decay H → ττ ! `h + 3 is one of the most promising discovery channels at the LHC. In this thesis, a study of the expected sensitivity of the ATLAS detector for this channel at a centreof- mass energy of 14 TeV is presented. For the first time, this study includes a full treatment of additional proton-proton interactions, so-called pile-up. The presence of pile-up significantly affects the signal selection efficiency and leads to a deterioration of the reconstructed Higgs boson mass, which is used as a discriminating observable. Two methods have been developed to estimate the dominant background processes from data. By replacing the muons in Z ! μμ events with simulated lepton decays, Z ! events can be modelled with high precision. The non-resonant background, t¯t production and W + jets, is estimated by selecting events where lepton and hadronic decay have the same electric charge. Assuming a dataset corresponding to an integrated luminosity of 30 fb−1, an expected signal significance between 3.0 and 4.4 is obtained for a Higgs boson mass between 115GeV and 135GeV. The expected significance decreases to 1.6–2.0 in the presence of pile-up.