TAU decays in a future B‐factory as a test of the standard model: A proposition for novel experiments

Abstract

The leptonic τ decay interaction, contrary to widespread belief, cannot be determined by measuring the Michel parameter ρ precisely. From muon decay, however, it is know that the interaction can be fixed by measuring the life time and four additional parameters. The measurement of three of these seems feasible with the advent of a B meson factory. They are: The longitudinal polarization of the μ+ from τ+ decay and the decay asymmetry described by the parameters ξ and δ. In addition, the helicity of the τ neutrino, ‖hντ‖, can be determined. The implications of these measurements on the decay interaction will be discussed.