Search for Baryon and Lepton Number Violating Decays of the $\tau$ Lepton

TL;DR

This study searched for rare tau lepton decays that violate lepton and baryon number conservation, using data from the CLEO II detector, and set new upper limits on their occurrence rates.

Contribution

First to set experimental upper limits on five tau decay modes that violate lepton and baryon number conservation.

Findings

No evidence of the targeted decay modes was observed.

Established new upper limits on branching fractions for these decays.

Provided first upper limits for three-body decay modes.

Abstract

We have searched for five decay modes of the tau lepton that simultaneously violate lepton and baryon number: tau -> anti-proton gamma, tau -> anti-proton pi0, tau -> anti-proton eta, tau -> anti-proton 2pi0, and tau -> anti-proton pi0eta. The data used in the search were collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR). The integrated luminosity of the data sample is 4.7 fb^{-1}, corresponding to the production of 4.3 x 10^6 tau+tau- events. No evidence is found for any of the decays, resulting in much improved upper limits on the branching fractions for the two-body decays and first upper limits for the three-body decays.