2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/206174We 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- nu) = (4.05 +- 0.25 +- 0.26) x 10^-5.11 pages, 7 figures, submitted to Phys. Lett. BHigh Energy Physics - Experimenttext