Search for Neutrinoless Tau Decays Involving the K0 Meson

TL;DR

This study searched for rare lepton flavor violating tau decays involving K0 mesons, setting new upper limits on their branching fractions due to no observed signals in the collected data.

Contribution

It provides the first upper limits on three-body tau decays involving K0 mesons and improves existing limits on two-body decays.

Findings

No evidence of lepton flavor violating tau decays was observed.

Set new upper limits on branching fractions for these rare decays.

First upper limits established for three-body decay modes.

Abstract

We have searched for lepton flavor violating decays of the tau lepton with one or two KS0 mesons in the final state. The data used in the search were collected with the CLEO II and II.V detectors at the Cornell Electron Storage Ring (CESR) and correspond to an integrated luminosity of 13.9 fb^-1 at the Upsilon(4S) resonance. No evidence for signals were found, therefore we have set 90% confidence level (C.L.) upper limits on the branching fractions B(tau -> e KS0) < 9.1e-7, B(tau -> muKS0) < 9.5e-7, B(tau -> e 2KS0) < 2.2e-6, and B(tau -> mu 2KS0) < 3.4e-6. These represent significantly improved upper limits on the two-body decays and first upper limits on the three-body decays.