Signature of a light charged Higgs boson from top quark pairs at the LHC

Abstract

The charged Higgs boson is of great theoretical interests which is predicted in various extensions of the standard model, and has been searched for at various collider experiments. In this paper, we study signatures of a light charged Higgs boson produced from top quark pairs at the LHC, with subsequent three-body decays into a W boson and a pair of bottom quarks. Cross sections on final states of two W bosons plus four bottom quarks have been measured by the ATLAS collaboration at LHC 13 TeV. We reinterpret the experimental data under the scenario of a light charged Higgs boson, and find improved agreements. We obtain the first limit from LHC direct searches on the total branching ratio of the three-body decay, Br(t → H + b)×Br(H + → W + b b), for a charged Higgs boson with mass smaller than the top quark, and the strongest direct constraints on parameter space of a class of type-I two-Higgs-Doublet models.