Search for lepton flavor violating decays tau- -> l- pi0, l- eta, l- eta'

TL;DR

This study searched for lepton flavor violating tau decays into specific mesons using Belle data, setting new upper limits that are significantly more restrictive than previous results.

Contribution

First search for these specific tau decay modes with Belle data, establishing the most stringent upper limits to date.

Findings

No evidence of lepton flavor violation found.

Upper limits on branching fractions are 10 to 64 times more restrictive.

Results constrain new physics models predicting such decays.

Abstract

We have searched for lepton flavor violating semileptonic tau decays using a data sample of 153.8/fb accumulated with the Belle detector at the KEKB e+e- collider. For the six decay modes studied, the observed yield is compatible with the estimated background and the following upper limits are set at the 90% confidence level: B(tau- -> e- eta) < 2.3 x 10^-7, B(tau- -> mu- eta) < 1.5 x 10^-7, B(tau- -> e- pi0) < 1.9 x 10^-7, B(tau- -> mu- pi0) < 4.1 x 10^-7, B(tau- -> e- eta') < 10 x 10^-7, and B(tau- -> mu- eta') < 4.7 x 10^-7. These results are 10 to 64 times more restrictive than previous limits.