Sensitivity of the ATLAS Experiment to discover the Decay H → ττ → ll + 4ν of the Standard Model Higgs Boson produced in Vector Boson Fusion

Abstract

A study of the expected sensitivity of the ATLAS experiment to discover the Standard Model Higgs boson produced via vector boson fusion (VBF) and its decay to H->tau->tau->ll +4nu is presented. The study is based on simulated proton-proton collisions at a centre-of- mass energy of 14TeV. For the first time the discovery potential is evaluated in the presence of additional proton-proton interactions (pile-up) to the process of interest in a complete and consistent way. Special emphasis is placed on the development of background estimation techniques to extract the main background processes Z->tautau and ttbar production using data. The ttbar background is estimated using a control sample selected with the VBF analysis cuts and the inverted b-jet veto. The dominant background process Z->tautau is estimated using Z->mumu events. Replacing the muons of the Z->mumu event with simulated tau-leptons, Z->tautau events are modeled to high precision. For the replacement of the Z boson decay products a dedicated method based on tracks and calorimeter cells is developed. Without pile-up a discovery potential of 3sigma to 3.4sigma in the mass range 115 GeV < MH < 130 GeV is obtained assuming an integrated luminosity of 30 fb^-1. In the presence of pile-up the signal sensitivity decreases to 1.7sigma to 1.9sigma mainly caused by the worse resolution of the reconstructed missing transverse energy.