τ-lepton decays

The study of τ-decays allows to test the standard model at different levels of sophistication: The space-time structure of the current can be determined by measuring the Michel-Parameter; if one combines the standard model with the CVC hypothesis one can predict the details of hadron production in the Jπ = 1- final state. Important input for weak interaction phenomenology follows from the analysis of the fragmentation of the uanti d(uanti s)-system into 0-, 1+ (1-) hadronic final states. Deviations of the experimental results from standard model based phenomenology would signal new physics, the hope for such an observation is an important stimulus of the studies of the heaviest lepton presently known. (orig.)