New Limits for Neutrinoless Tau Decays

TL;DR

This paper reports on a search for neutrinoless tau decays into specific final states, setting new upper limits on their branching fractions using data from the CLEO II detector, thus advancing the understanding of lepton number violation.

Contribution

The study updates previous searches by including six additional decay channels and provides the first limits for several decay modes, improving constraints on neutrinoless tau decays.

Findings

No signal observed in any decay channel.

Set upper limits on branching fractions for 28 decay modes.

Some limits are more stringent than previous results.

Abstract

Neutrinoless 3-prong tau lepton decays into a charged lepton and either two charged particles or one neutral meson have been searched for using 4.79 fb^{-1} of data collected with the CLEO II detector at CESR. This analysis represents an update of a previous study and the addition of six decay channels. In all channels the numbers of events found are compatible with background estimates and branching fraction upper limits are set for 28 different decay modes. These limits are either more stringent than those set previously or represent the first attempt to find these decays.