Search for pair production of the heavy vectorlike top partner in same-sign dilepton signature at the HL-LHC

Abstract

New vectorlike quarks are predicted in many new physics scenarios beyond the Standard Model (SM) and could potentially be discovered at the LHC. Based on a simplified model including a singlet vectorlike top partner with charge $2/3$, we investigate the process $pp\ensuremath{\rightarrow}TT$ via a $t$ channel induced by the couplings between the top partner with the first-generation SM quarks. We calculate the production cross section and further study the observability of the heavy top partner in the channel $T\ensuremath{\rightarrow}Wq$ at the high-luminosity LHC (HL-LHC) using final states with same-sign dileptons (electrons or muons), two jets, and missing transverse momentum. At the 14 TeV LHC with an integrated luminosity of $3000\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, the $2\ensuremath{\sigma}$ exclusion limits, as well as the $5\ensuremath{\sigma}$ discovery reach in the parameter plane of the two variables ${g}^{*}\ensuremath{-}{R}_{L}$, are respectively obtained at the HL-LHC. We also obtain the $2\ensuremath{\sigma}$ exclusion limit on the coupling strength parameter ${g}^{*}$ in the case in which the vectorlike top partner is coupled only to the first-generation quarks.