Study of Michel spectrum of tau decay

Abstract

This thesis is the beginning of a larger project to use BaBar to examine weak couplings through leptonic [tau] decay. I will use the ratio of Br... and Br... and the Michel parameters [rho] and [eta]. which describe the momenta spectrum of the daughter leptons. I studied using a simultaneous fit to the [tau] --> e and [tau] --> [mu] momentum spectra, using [rho], [eta], the ratio Br..., and total number of events as the fit variables. I created a simple Monte Carlo simulation which generated a. sample data spectrum and fit it for the Michel parameters [rho] and [eta]. I used the Monte Carlo to assess the impact of the uncertainties in the detector response function on the measurement of the ratio Br... My conclusion is that the three efficiency uncertainties equally have the greatest effect on the measurement of the number of events. The energy offset affects the measurement of Br... and that the energy scale and offset uncertainties have a non-negligible effect on [rho] and [eta].