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

TL;DR

This paper explores the potential of future $e^+ e^-$ colliders to discover weak isosinglet vectorlike leptons that decay via small mixing with tau leptons, which are difficult to detect at hadron colliders.

Contribution

It demonstrates how $e^+ e^-$ colliders can effectively discover and analyze these leptons, including mass reconstruction and branching ratio measurement.

Findings

$e^+ e^-$ colliders can discover $ au'$ leptons beyond LHC reach.

Mass peaks of $ au'$ can be reconstructed in various signal regions.

Branching ratios of $ au'$ can be measured accurately.

Abstract

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.