Search for Heavy Neutral and Charged Leptons in e+ e- Annihilation at LEP

TL;DR

This paper reports a search for heavy neutral and charged leptons in electron-positron collisions at LEP, finding no evidence and setting lower mass limits for these hypothetical particles.

Contribution

It is the first comprehensive search considering various theoretical models for heavy leptons at LEP energies, establishing new mass exclusion limits.

Findings

No evidence for heavy leptons was observed.

Lower mass limits were set for neutral and charged heavy leptons.

The study considered multiple theoretical models including sequential, vector, and mirror types.

Abstract

A search for exotic unstable neutral and charged heavy leptons as well as for stable charged heavy leptons is performed with the L3 detector at LEP. Sequential, vector and mirror natures of heavy leptons are considered. No evidence for their existence is found and lower limits on their masses are set.