A General Treatment of Tau Semi-Leptonic Decays

Abstract

The most general Lorentz invariant spin-correlation functions for $\tau ^{-}\rightarrow \rho ^{-}\nu ,a_1^{-}\nu ,K^{*-}\nu , \pi ^{-}\nu ,K^{-}\nu $ are expressed in terms of eight semi-leptonic parameters. They are physically defined in terms of tau-decay partial-width-intensities for polarized-final-states. The parameters are also expressed in terms of a ``$(V-A)\ +\ $additional chiral coupling'' structure in the ${J^{Charged}}_{Lepton}$ current, so as to bound the scales $\Lambda $\ for ``new physics'' such as arising from leptonic CP violation, tau weak magnetism, weak electricity, and/or second-class currents. The two tests for leptonic CP violation in $\tau \rightarrow \rho \nu \ $ decay are generalized to $\tau \rightarrow a_1\nu \ $ decay and to two additional tests if there are $\nu _R\ $ and $\bar \nu _L\ $ couplings.