A measurement of the tau(-)-> e(-)(nu)over-bar(e)nu(tau) branching ratio

The branching ratio for the decay tau(-) --> e(-) (e)nu(tau) has been measured using Z(0) decay data collected by the OPAL experiment at LEP. In total 33 073 tau(-) --> e(-) (e)nu(tau) candidates were identified from a sample of 186 197 selected tau. decays, giving a branching ratio of B(tau(-) --> e(-) (e)nu(tau)) = (17.81 +/- 0.09 (stat) +/- 0.06 (syst))%. This result is combined with other measurements to test e - mu and mu - tau universality in charged-current weak interactions. Additionally, the strong coupling constant alpha(s)(m(tau)(2)) has been extracted from B(tau(-) --> e(-) (e)nu(tau)) and evolved to the Z(0) mass scale, giving alpha(s)(m(Z)(2)) = 0.1204 +/- 0.0011 (exp) +/- 0.0019 (theory). (C) 1999 Published by Elsevier Science B.V. All rights reserved.