First observation of the decay τ-→φK-υτ

We present the first observation of tau lepton decays to hadronic final states with a phi-meson. This analysis is based on 401 fb(-1) of data accumulated at the Belle experiment. The branching fraction obtained is B(tau(-) -> phi K(-)v(tau)) = (4.05 +/- 0.25 +/- 0.26) x 10(-5). (c) 2006 Elsevier B.V. All rights reserved.