Search for Lepton Flavor Violating tau Decays into Three Leptons

TL;DR

This paper reports a search for lepton flavor violating tau decays into three leptons using Belle detector data, setting new upper limits on branching fractions and finding no evidence of such decays.

Contribution

First search for tau to three lepton decays with Belle data, establishing more stringent upper limits on branching fractions.

Findings

No evidence for lepton flavor violating tau decays.

Set upper limits on branching fractions between 2.0 and 4.1 x 10^-8.

Results improve previous limits by factors of 4.9 to 10.

Abstract

We search for lepton-flavor-violating tau decays into three leptons (electron or muon) using 535 fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. No evidence for these decays is observed, and we set 90% confidence level upper limits on the branching fractions of (2.0-4.1)x10^-8. These results improve upon our previously published upper limits by factors of 4.9 to 10.