Constraints on flavor-changing neutral-current $Htq$ couplings from the signal of $tH$ associated production with QCD next-to-leading order accuracy at the LHC

TL;DR

This paper investigates flavor-changing neutral-current $Htq$ couplings through $tH$ associated production at the LHC, incorporating complete QCD NLO corrections, and assesses the potential for detection or setting limits on these couplings.

Contribution

It provides the first comprehensive analysis of QCD NLO effects on $tH$ production via FCNC couplings, including decay processes, and evaluates LHC detection prospects.

Findings

QCD NLO corrections increase cross sections by ~50%.

After cuts, corrections reduce to ~11% for $Htu$ and negligible for $Htc$.

LHC can observe signals at 5σ in some parameter regions or set upper limits.

Abstract

We study a generic Higgs boson and a top quark associated production via model-independent flavor-changing neutral-current couplings at the LHC, including complete QCD next-to-leading order (NLO) corrections to the production and decay of the top quark and the Higgs boson. We find that QCD NLO corrections can increase the total production cross sections by about 48.9% and 57.9% for the $Htu$ and $Htc$ coupling induced processes at the LHC, respectively. After kinematic cuts are imposed on the decay products of the top quark and the Higgs boson, the QCD NLO corrections are reduced to 11% for the $Htu$ coupling induced process and almost vanish for the $Htc$ coupling induced process. Moreover, QCD NLO corrections reduce the dependence of the total cross sections on the renormalization and factorization scales. We also discuss signals of the $tH$ associated production with the decay mode $t \rightarrow bl^{+}E \slash_{T}, H \rightarrow b\bar{b}$ and $t\bar{t}$ production with the decay mode $\bar{t} \rightarrow H\bar{q}, t\rightarrow bl^{+}E \slash_{T}$. Our results show that, in some parameter regions, the LHC may observe the above signals at the $5\sigma$ level. Otherwise, the upper limits on the FCNC $Htq$ couplings can be set.