Measuring hadronic currents and weak coupling constants in τ→ν3π

Abstract

A theoretical description of the decay τ→ν3π in a covariant tensor language employing the isobar model is presented. Special emphasis is devoted to the dominating decay mode into νa ₁ witha ₁→ρπ inS- andD-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 asS- andD-wave in the literature. Implications of a possible PCAC suppressed π′(1300) as well as exotic contributions are discussed. Analysis methods for the experimental determination of these effects, theD/S ratio of thea ₁ and the weak τ decay constants are presented. For the latter a new moment is introduced and the model dependence is discussed.