Searches for the FCNC couplings from top-Higgs associated production signal with $h\to \gamma\gamma$ at the LHC

TL;DR

This study investigates the potential to detect top-Higgs FCNC couplings at the LHC via a specific process involving Higgs decay to photons, providing sensitivity estimates for branching ratios and methods to distinguish different couplings.

Contribution

It presents a detailed analysis of the observability of top-Higgs FCNC couplings through a novel process at the LHC, including sensitivity projections and discrimination strategies.

Findings

LHC can observe signals at 5σ in certain parameter regions.

Branching ratios can be probed down to 0.036% for t→uh and 0.13% for t→ch at 3σ.

Charge ratio analysis helps distinguish signal from background and between different FCNC couplings.

Abstract

In this paper, we study the observability of the top-Higgs flavor changing neutral current (FCNC) $tqh$ coupling through the process $pp\to qg\to t(\to \ell^{+}b\nu)h(\to \gamma\gamma)$ at the Large Hadron Collider~(LHC), where $\ell=e, \mu$. Our numerical results show that, in some parameter regions, the LHC may observe the above signals at the $5\sigma$ level. Otherwise, the branching ratios $Br(t\to uh)$ and $Br(t\to ch)$ can be respectively probed to $0.036\%$ and $0.13\%$ at $3\sigma$ level at 14 TeV LHC with the high integrated luminosity of 3000 fb$^{-1}$. On the other hand, studying the charge ratio for the lepton in top quark decay can be not only used to discriminate between signal and backgrounds, but also used to discriminate between $tuh$ and $tch$ couplings, for which anomalous single top production comes from the up initiated channel and charm initiated channel.