Search for heavy neutral Higgs bosons A and H in the $\mathrm{t\bar{t}}$Z channel in proton-proton collisions at 13 TeV

TL;DR

This paper reports a search for heavy neutral Higgs bosons A and H in the t-tbar-Z channel using 13 TeV proton-proton collision data, setting limits on their production and decay, and interpreting results within two-Higgs-doublet models.

Contribution

First search targeting the pp → A → ZH with H → t-tbar in all-hadronic and leptonic Z decays at 13 TeV, extending previous limits on heavy Higgs bosons.

Findings

No signal observed in the data.

Upper limits set on cross section times branching ratio up to 2100 GeV.

Results interpreted within two-Higgs-doublet models.

Abstract

A direct search for new heavy neutral Higgs bosons A and H in the $\mathrm{t\bar{t}}$Z channel is presented, targeting the process pp $\to$ A $\to$ ZH with H $\to$ $\mathrm{t\bar{t}}$. For the first time, the channel with decays of the Z boson to muons or electrons in association with all-hadronic decays of the $\mathrm{t\bar{t}}$ system is targeted. The analysis uses proton-proton collision data collected at the CERN LHC with the CMS experiment at $\sqrt{s}$ = 13 TeV, which correspond to an integrated luminosity of 138 fb$^{-1}$. No signal is observed. Upper limits on the product of the cross section and branching fractions are derived for narrow resonances A and H with masses up to 2100 and 2000 GeV, respectively, assuming A boson production through gluon fusion. The results are also interpreted within two-Higgs-doublet models, where A and H are CP-odd and CP-even states, respectively, complementing and substantially extending the reach of previous searches.