Isosinglet vectorlike leptons at $e^{+}{e}^{-}$ colliders

We study weak isosinglet vectorlike leptons that decay through a small mixing with the tau lepton, for which the discovery and exclusion reaches of the Large Hadron Collider and future proposed hadron colliders are limited. We show how an $e^{+}{e}^{-}$ collider may act as a discovery machine for these ${\tau }^{\prime }$ particles, demonstrate that the ${\tau }^{\prime }$ mass peak can be reconstructed in a variety of distinct signal regions, and explain how the ${\tau }^{\prime }$ branching ratios may be measured.