Enhancing $thj$ Production from Top-Higgs FCNC Couplings

TL;DR

This paper investigates the enhancement of $thj$ production via top-Higgs FCNC couplings at the LHC, demonstrating increased cross sections and potential for probing rare top decays with high sensitivity.

Contribution

It provides a detailed analysis of $pp o thj$ production enhancement and explores the observability of FCNC couplings at the LHC, including sensitivity estimates for rare top decays.

Findings

Cross section of $pp \to thj$ can be significantly increased over SM predictions.

Full cross section with $\kappa_{tch}$ exceeds resonant contribution by ~12-16%.

Branching ratios $Br(t\to qh)$ can be probed down to ~0.12-0.26% at 14 TeV LHC.

Abstract

In this paper, we study the single top and Higgs associated production $pp \to thj$ in the presence of top-Higgs FCNC couplings($\kappa_{tqh}, q=u,c$) at the LHC. Under the current constraints, we find that the cross section of $pp \to thj$ can be sizably enhanced in comparison with the SM predictions at 8 and 14 TeV LHC. We also find that the full cross section of $pp \to thj$ with $\kappa_{tch}$ is larger than the resonant cross section of $pp \to t\bar{t} \to thj$ by a factor 1.16 at 8 TeV LHC and 1.12 at 14 TeV LHC, respectively. We further explore the observability of top-Higgs FCNC couplings through $pp \to t(\to b\ell^{+} \nu_{\ell}) h( \to \gamma\gamma) j$ and find that the branching ratios $Br(t\to qh)$, $Br(t \to uh)$ and $Br(t \to ch)$ can be respectively probed to $0.12\%,~0.23\%$ and $~0.26\%$ at $3\sigma$ sensitivity at 14 TeV LHC with ${\cal L} =3000$ fb$^{-1}$.