"Perturbative QCD and tau-decays"

Konstantin Chetyrkin

Abstract:

The current status of the higher order QCD corrections to the width of

the tau is discussed. We report on the result of the first complete

determination of the the strange quark mass to the order alpha_s^3.

We discuss the perspectives of the calculation of the not-yet-computed

contribution of order alpha_s^4 to the tau decay rate and its possible

influence on the extraction of the value of the QCD coupling

constant alpha_s from tau-decays.