Search for a Light Charged Higgs Boson Decaying to a W Boson and a CP-Odd Higgs Boson in Final States with eμμ or μμμ in Proton-Proton Collisions at √s = 13 TeV

Abstract

A search for a light charged Higgs boson (\({H}^{+}\)) decaying to a \(W\) boson and a \(CP\)-odd Higgs boson (\(A\)) in final states with \(e\mu \mu \) or \(\mu \mu \mu \) is performed using data from \(pp\) collisions at \(\sqrt{s}=13\text{}\text{}\mathrm{TeV}\), recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of \(35.9\text{}\text{}{\mathrm{fb}}^{-1}\). In this search, it is assumed that the \({H}^{+}\) boson is produced in decays of top quarks, and the \(A\) boson decays to two oppositely charged muons. The presence of signals for \({H}^{+}\) boson masses between 100 and 160 GeV and \(A\) boson masses between 15 and 75 GeV is investigated. No evidence for the production of the \({H}^{+}\) boson is found. Upper limits at 95% confidence level are obtained on the combined branching fraction for the decay chain, \(t\to b{H}^{+}\to b{W}^{+}A\to b{W}^{+}{\mu }^{+}{\mu }^{-}\), of \(1.9×{10}^{-6}\) to \(8.6×{10}^{-6}\), depending on the masses of the \({H}^{+}\) and \(A\) bosons. These are the first limits for these decay modes of the \({H}^{+}\) and \(A\) bosons.