An investigation of the Lorentz structure in tau decays

Abstract

This paper describes a measurement of the Michel parameters, η, ϱ, Ξ, Ξδ, the average ν τ helicity, h ν τ , and the anomolous tensor coupling constant, κ τ W , in τ lepton decays using the DELPHI detector. The τ + τ − pairs were produced at the LEP e + e − collider at CERN between 1992 and 1995. The Michel parameters, together with a measurement of the τ polarisation, P τ, were extracted in a simultaneous fit to the two dimensional momentum spectra of leptonic and semi-leptonic τ decays. The anomalous tensor coupling constant, κ τ W , was measured using the same selected data.