Searches for lepton flavor violating decays $\tau^\pm \to \ell^\pm\gamma$, $\tau^\pm \to \ell^\pm P^0$ (where $\ell^- = e^-, \mu^-$, and $P^0$ = $\pi^0, \eta, \eta^{\prime}$) at B-Factories: Status and Combinations

TL;DR

This paper reviews the current experimental limits on lepton flavor violating tau decays to lighter leptons and mesons, combining data from BaBar and Belle to improve the upper limits on branching fractions.

Contribution

It provides the first combined analysis of BaBar and Belle data to set more stringent upper limits on lepton flavor violating tau decays.

Findings

Combined upper limits on branching fractions improved.

No evidence found for lepton flavor violation in tau decays.

Sets new constraints for theoretical models of new physics.

Abstract

The present experimental status of searches for lepton flavor violating decays of the $\tau$ lepton to a lighter mass lepton and a photon or a pseudoscalar meson is presented. The results obtained are from $e^+e^-$ annihilation data collected at a center-of-mass energy near 10.58 GeV by the \babar and the Belle detectors. In order to benefit from larger available datasets, the first $\babar-$Belle combinations of upper limits on the branching fractions of lepton flavor violating $\tau$-decays are obtained.