Search for charged Higgs bosons produced in top-quark decays or in association with top quarks and decaying via H → τντ in 13 TeV pp collisions with the ATLAS detector

Abstract

Charged Higgs bosons produced either in top-quark decays or in association with a top quark,subsequently decaying via H RIGHTWARDS ARROW τντ, are searched for in 140 fb-1 ffiffiffi of proton-proton collision data atsp1/4 13 TeV recorded with the ATLAS detector. Depending on whether the top quark is producedtogether with the H decays hadronically or semileptonically, the search targets τ þ jets or τ þ lepton finalstates, in both cases with a τ-lepton decaying into a neutrino and hadrons. No significant excess over theStandard Model background expectation is observed. For the mass range of 80 <= mH <= 3000 GeV, upperlimits at 95% confidence level are set on the production cross section of the charged Higgs boson times thebranching fraction BðH RIGHTWARDS ARROW τντÞ in the range 4.5 pb-0.4 fb. In the mass range 80-160 GeV, assuming theStandard Model cross section for t-t production, this corresponds to upper limits between 0.27% and 0.02%on Bðt RIGHTWARDS ARROW bHÞ x BðH RIGHTWARDS ARROW τντÞ.