Measurement of the branching ratio for D-s(-)->tau(-)(nu)over-bar(tau) decays

Using about 3.9 million hadronic Z decays from e(+)e(-) collisions recorded by the OPAL detector at LEP at centre-of-mass energies,roots approximate to M-Z, the branching ratio for the decay D-s(-)--> tau (-)(v) over bar (tau) has been measured to be BR(D-s(-) --> tau (-)(v)over bar>) = (7.0 +/- 2.1(stat) +/- 2.0(syst))%. This result can be used to derive the decay constant of the D-s(-) meson: f(Ds) = (286 +/- 44(stat) +/- 41 (syst)) MeV. (C) 2001 Elsevier Science B.V. All rights reserved.