Search for single production of the heavy vectorlike $T$ quark with $T\to th$ and $h\to \gamma\gamma$ at the high-luminosity LHC

TL;DR

This paper explores the potential to discover heavy vectorlike T quarks at the high-luminosity LHC by analyzing their single production and decay into a top quark and Higgs boson, with the Higgs decaying into two photons.

Contribution

It presents a detailed analysis of the single production of vectorlike T quarks via couplings with first and third generation quarks, including the impact of mixing on production rates and discovery prospects.

Findings

Enhanced production cross section due to mixing with first generation quarks.

Exclusion limits and discovery reach for T quark masses of 600, 800, and 1000 GeV.

Potential to discover or exclude T quarks at the HL-LHC with 3 ab$^{-1}$ luminosity.

Abstract

The vectorlike top partners $T$ are predicted in many extensions of the Standard Model (SM). In a simplified model including a single vectorlike $T$ quark with charge $2/3$, we investigate the process $pp \to Tj$ induced by the couplings between the top partner with the first and the third generation quarks at the LHC. We find that the mixing with the first generation can enhance the production cross section. We further study the observability of the single heavy top partner through the process $pp \to T(\to th)j\to t(\to b \ell \nu_{\ell})h( \to \gamma\gamma) j$ at the high-luminosity~(HL)-LHC~(a 14 TeV $pp$ collider with an integrated luminosity of 3 ab$^{-1}$). For three typical heavy $T$ quark masses $m_T=600,800$ and 1000 GeV, the $3\sigma$ exclusion limits, as well as the $5\sigma$ discovery reach in the parameter plane of the two variables $g^{\ast}-R_L$, are respectively obtained at the HL-LHC.