Production of heavy Higgs bosons and decay into top quarks at the LHC

TL;DR

This paper calculates the production and decay of heavy Higgs bosons into top quark pairs at the LHC, including NLO QCD corrections and interference effects, providing detailed predictions for experimental searches.

Contribution

It presents the first NLO QCD calculations of heavy Higgs production and decay into top pairs, incorporating interference and background effects in a two-Higgs-doublet model.

Findings

NLO corrections significantly affect Higgs signal predictions.

Interference effects alter the $t\bar{t}$ invariant mass distributions.

Estimated detection significances for heavy Higgs signals at 13 TeV LHC.

Abstract

We investigate the production of heavy, neutral Higgs boson resonances and their decays to top-quark top-antiquark ($t\bar{t}$) pairs at the Large Hadron Collider (LHC) at next-to-leading order (NLO) in the strong coupling of quantum chromodynamics (QCD). The NLO corrections to heavy Higgs boson production and the Higgs-QCD interference are calculated in the large $m_t$ limit with an effective K-factor rescaling. The nonresonant $t\bar{t}$ background is taken into account at NLO QCD including weak-interaction corrections. In order to consistently determine the total decay widths of the heavy Higgs bosons, we consider for definiteness the type-II two-Higgs-doublet extension of the standard model and choose three parameter scenarios that entail two heavy neutral Higgs bosons with masses above the $t\bar{t}$ threshold and unsuppressed Yukawa couplings to top quarks. For these three scenarios we compute, for the LHC operating at 13 TeV, the $t\bar{t}$ cross section and the distributions of the $t\bar{t}$ invariant mass, of the transverse top-quark momentum and rapidity, and of the cosine of the Collins-Soper angle with and without the two heavy Higgs resonances. For selected $M_{t\bar{t}}$ bins we estimate the significances for detecting a heavy Higgs signal in the $t\bar{t}$ dileptonic and lepton plus jets decay channels.