Study of high-multiplicity 3-prong and 5-prong tau decays at BABAR

TL;DR

This paper reports measurements of branching fractions for high-multiplicity tau decays, providing new limits on rare decay modes and searching for isospin-forbidden processes using a large data sample from the BaBar experiment.

Contribution

It presents the first measurements and upper limits for several high-multiplicity tau decay modes, including rare and forbidden processes, using extensive data from the BaBar detector.

Findings

Measured branching fractions for several tau decay modes.

Set upper limits on isospin-forbidden decay u- ta'(958).

Found no evidence for charged kaons in these decay channels.

Abstract

We present measurements of the branching fractions of 3-prong and 5-prong tau decay modes using a sample of 430 million tau lepton pairs, corresponding to an integrated luminosity of 468 fb-1, collected with the BaBar detector at the PEP-II asymmetric energy e+e- storage rings. The \tau- --> (3\pi)- \eta \nu, \tau- --> (3\pi)- \omega \nu, and \tau- --> \pi- f_1(1285)\nu, branching fractions are presented as well as a new limit on the branching fraction of the isospin-forbidden, second-class current, \tau- --> \pi-\eta'(958)\nu, decay. We find no evidence for charged kaons in these decay modes and place the first upper limits on their branching fractions.