Radiative tau production and decay.

Abstract

A study of the muon decay channel of the τ lepton with the presence of a photon has been carried out to verify theoretical predictions for the production rate of e + e - → τ + τ - γ and for the branching ratio of τ - → ν τ µ - ν µ γ. Included in this study is the first direct measurement of radiative tau decay. Using e + e - annihilation data taken at 29 GeV center-of-mass energy with the Mark II detector, we find the ratio of the measured τ - → ν τ µ - ν µ γ branching fraction to the expected value from QED to be 1.03 ± 0.42. The ratio of measured-to-predicted number of events from radiative T production, e + e - → τ + τ - γ, where one of the τ's decay to μνν is found to be 0.91 ± 0.20. We have not seen an indication of anomalous behavior in radiative tau events.