An upper limit on the branching ratio for tau decays into seven charged particles

TL;DR

This paper reports a search for tau lepton decays into seven charged particles, setting a new upper limit on the branching ratio due to no observed candidate events in the data.

Contribution

The study establishes the first upper limit on the branching ratio for tau decays into seven charged particles using OPAL data from 1990-1995.

Findings

No candidate events found for tau decays into seven charged particles.

Upper limit on the branching ratio is 1.8 x 10^-5 at 95% confidence level.

Provides constraints for theoretical models of tau decay channels.

Abstract

We have searched for decays of the tau lepton into seven or more charged particles, using data collected with the OPAL detector from 1990 to 1995 in e^+e^- collisions at sqrt(s) ~ M_Z. No candidate events were found and an upper limit on the branching ratio for tau decays into seven charged particles of 1.8 x 10^-5 at the 95% confidence level was determined.