Search for a light charged Higgs boson in t -> H+-b decays, with H+- -> cb, in the lepton+jets final state in proton-proton collisions at CMS = 13 TeV with the ATLAS detector
Abstrakt
A search for a charged Higgs boson, H+-, produced in top-quark decays, t !
H+-b, is presented. The search targets H+- decays into a bottom and a charm quark,
H+- ! cb. The analysis focuses on a selection enriched in top-quark pair production, where one top quark decays into a leptonically decaying W boson and a bottom quark, and the other top quark decays into a charged Higgs boson and a bottom quark. This topology leads to a lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of jets containing b-hadrons, and deploys a neural network classifier that uses the kinematic differences between the signal and the background. The search uses a dataset of proton-proton collisions collected at a centre-of-mass energy p s = 13TeV between 2015 and 2018 with the ATLAS detector at CERN's Large Hadron Collider, amounting to an integrated luminosity of 139 fb-1.
Observed (expected) 95% confidence-level upper limits between 0.15% (0.09%) and 0.42%
(0.25%) are derived for the product of branching fractions B(t ! H+-b) x B(H+- ! cb) for charged Higgs boson masses between 60 and 160 GeV, assuming the SM production of the top-quark pairs.