Search for Higgs boson production in association with a top quark pair in pp collisions

Andrew Brinkerhoff

doi:10.1088/1742-6596/452/1/012006

Abstract

We present a search for the standard model Higgs boson produced in association with a top quark pair in 5 fb−1 of 7 TeV pp collision data. We look for events where the Higgs boson decays to bb̄ and the top quark pair decays to either lepton plus jets (tt̄ → ℓνjjbb̄) or dileptons (tt̄ → ℓνℓνbb̄), where ℓ is an electron or muon. The major background to our signal is top pair production. We use artificial neural networks to discriminate between background and signal events. We perform a simultaneous fit for signal and background fractions using the neural network output distributions. Our expected limit on Higgs boson production cross section times H → bb̄ branching ratio for a Higgs boson mass of 125 GeV/c2 is 4.6 times the standard model expectation, while the observed limit is 3.8 times the standard model expectation.

Highlights

We present a search for Higgs boson production in the ttH channel using data taken in 2011 by the CMS detector [2], where H → bband the top pair decays semi-leptonically or fully leptonically
If a Higgs-like excess is observed in the data, measuring the values of these couplings will help to determine whether the object responsible for the excess has the properties expected from a SM Higgs boson
The results presented in these proceedings represent the first CMS search for SM Higgs boson production in association with a top quark pair decaying semi-leptonically or fully leptonically

Summary

Introduction

We present a search for Higgs boson production in the ttH channel using data taken in 2011 by the CMS detector [2], where H → bband the top pair decays semi-leptonically (tt → νjjbb) or fully leptonically (tt → ννbb). This analysis selects events consistent with the production of a top quark pair in association with a Higgs boson, where the top quark pair decays by either the lepton + jets (tt → νjjbb) or dilepton (tt → ννbb) modes and the Higgs boson decays to a pair of bottom quarks. For the lepton + jets case, we select events containing an energetic, isolated, charged electron or muon, and at least four energetic jets, two or more of which should be identified as containing a bottom quark hadron (b-tagged).

Results

Conclusion