MEASURING HADRONIC CURRENTS AND WEAK-COUPLING CONSTANTS IN TAU-]NU-3-PI

A theoretical description of the decay tau --> v3-pi in a covariant tensor language employing the isobar model is presented. Special emphasis is devoted to the dominating decay mode into va1 with a1 --> p-pi in S- and D-wave orbital momentum eigenstates. These formulae are useful for quantitative tests of the standard model prediction for the parity violation effect recently observed by the ARGUS experiment. We emphasize the difference between these orbital angular momentum amplitudes and Born term amplitudes erroneously identified as S- and D-wave in the literature. Implications of a possible PCAC suppressed pi'(1300) as well as exotic contributions are discussed. Analysis methods for the experimental determination of these effects, the D/S ratio of the a1 and the weak tau decay constants are presented. For the latter a new moment is introduced and the model dependence is discussed.