Search for a Light Charged Higgs Decaying into cb in the CMS experiment with pp collisions at √s=8 TeV

Abstract

This document describes the first attempt to search for a charged Higgs boson decaying to c¯b in top quark events in a CMS data corresponding to 19.7 fb−1 at √s= 8 TeV in LHC. The tt event in lepton+jets channel consists of a lepton, missing transverse energy, two b-jets, and two light quark jets in the final state. If a charged Higgs is produced in place of the hadronic W and it decays to cb, one more b-jet will be found in the final state. Selected tt events are thrown to a kinematic fitter for the full reconstruction constraining both leptonic and hadronic top quark mass, and leptonic W to their PDG values. The di-jet invariant mass is the only free parameter and reveals W mass from the SM tt events. This analysis looks for an excess over the hadronic W in the di-jet mass distribution in two b-tagged and three b-tagged events simultaneously.Upper limits on the branching ratio of a top quark decaying to a charged Higgs and b quark with 95% C.L. are placed at ~ 1% for H± mass of 90 to 150 GeV/c2 in null hypothesis.