Review of Rare and Forbidden $\tau$ Decays

Abstract

This is a review of rare and forbidden decays of the $\tau$ lepton. For the rare decays, this includes new results on the chiral anomaly decay \taupietapio, new upper limits on the second-class-current decay \taupieta, and the observations of the Cabibbo-suppressed decay \tauketa and the internal conversion decay \taueee. For the forbidden decays, there are new upper limits on the radiative decays \tauegamma and \taumugamma. Some forbidden decays which have not been previously searched for are also suggested