A measurement of the tau to mu nu nu branching ratio

Abstract

The tau -> mu nu nu branching ratio has been measured using data collected from 1990 to 1995 by the OPAL detector at the LEP collider. The resulting value of B(tau->mu nu nu) = 0.1734 +/- 0.0009(stat) +/- 0.0005(syst) has been used in conjunction with other OPAL measurements to test lepton universality, yielding the coupling constant ratios g(mu)/g(e) = 1.0005 +/- 0.0043 and g(tau)/g(e) = 1.0031 +/- 0.0047, in good agreement with the Standard Model prediction of unity, and also to determine a value for the Michel parameter eta = 0.004 +/- 0.036. This is subsequently used to find a model-dependent limit of the mass for the charged Higgs boson, m(Higgs) > 1.30 tan(beta), in the Minimal Supersymmetric Standard Model.

Invited talk at the Seventh International Workshop on Tau Lepton Physics, (Tau02), Santa Cruz, Ca. USA, Sept. 2002, 10 pages, LaTex, 11 eps figures, PSN tau02_03