Michel Parameters in $\tau$ Decays: Averages and Interpretation

The new measurements of Michel parameters in tau decays are combined to world averages. From these measurements model independent limits on non-standard model couplings are derived and interpretations in the framework of specific models are given. A lower limit of 2.5 tan(beta) GeV on the mass of a charged Higgs boson in models with two Higgs doublets can be set and a 229 GeV limit on a right-handed W-boson in left-right symmetric models (95% c.l.).