Study of the τ−→π−π+π−π0ντ and τ−→π−π−π+ηντ decays using the BaBar Detector

The τ−→π−π+π−π0ντ and τ−→π−π−π+ηντ decays have been studied with the BaBar detector. Preliminary branching fractions on the two modes are presented. The τ−→π−π+π−π0ντ mode is found to have a large contribution from the τ−→ωπ−ντ decay. The τ−→π−π−π+ηντ decay is studied using the η→γγ mode and the τ−→f1(1285)π−ντ decay is seen to be the primary source of these decays. A 90% confidence level upper limit is placed on the τ−→η′(958)π−ντ decay which proceeds through a second-class current and is expected to be forbidden in the limit of perfect isospin symmetry.