Search for charged Higgs bosons decaying into top and bottom quarks at $\sqrt{s}$ = 13 TeV with the ATLAS detector

TL;DR

This paper reports a search for heavy charged Higgs bosons decaying into top and bottom quarks using 13 TeV proton-proton collision data from the ATLAS detector, setting exclusion limits on production cross-sections across a wide mass range.

Contribution

It presents the first search for charged Higgs bosons in the $tb$ decay channel at 13 TeV with detailed analysis techniques and exclusion limits in the context of the MSSM.

Findings

No significant excess observed above background.

Exclusion limits on production cross-section range from 2.9 pb to 0.070 pb.

Results interpreted within two MSSM benchmark scenarios.

Abstract

A search for charged Higgs bosons heavier than the top quark and decaying via $H^\pm \rightarrow tb$ is presented. The data analysed corresponds to 36.1 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV and was recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark, $pp \rightarrow tb H^\pm$, is explored in the mass range from $m_{H^\pm}$ = 200 to 2000 GeV using multi-jet final states with one or two electrons or muons. Events are categorised according to the multiplicity of jets and how likely these are to have originated from hadronisation of a bottom quark. Multivariate techniques are used to discriminate between signal and background events. No significant excess above the background-only hypothesis is observed and exclusion limits are derived for the production cross-section times branching fraction of a charged Higgs boson as a function of its mass, which range from 2.9 pb at $m_{H^\pm}$ = 200 GeV to 0.070 pb at $m_{H^\pm}$ = 2000 GeV. The results are interpreted in two benchmark scenarios of the Minimal Supersymmetric Standard Model.