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

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→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→T(→th)j→t(→bℓνℓ)h(→γγ)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 mT=600, 800 and 1000 GeV, the 3σ exclusion limits, as well as the 5σ discovery reach in the parameter plane of the two variables g*-RL, are respectively obtained at the HL-LHC.