Search for lepton flavour violation in Z decays

Abstract

We have searched for lepton flavour violation in Z boson decays into lepton pairs using all data collected with the L3 detector during the 1990, 1991 and 1992 runs on an event sample corresponding to 1 500 000 Z's produced. At the 95% confidence level the upper limits on the branching ratio for Z→eμ is 0.6×10⁻⁵ and for Z→μτ this is 1.9×10⁻⁵.