Pair production of the isosinglet vector-like leptons at the colliders*

Abstract Within minimal extensions of the Standard Model, including weak isosinglet vector-like leptons (VLLs, ), we investigate the pair production of VLLs at future colliders, incorporating the full simulation of the initial state radiation and beam polarization effects. Two characteristic decay channels are analyzed: (i) the dilepton final state ( ) from with and , and (ii) the single-lepton final state from with and . By performing detailed detector-level simulations of both signal and background processes, we obtain the exclusion limits and discovery potential as functions of the VLL mass and integrated luminosity. The results demonstrate that future colliders can probe VLL masses up to GeV at TeV, 740 GeV at TeV, and 1440 GeV at TeV, significantly exceeding LHC sensitivity while enabling precision measurements in the clean lepton-collider environment.