Tau Decays into Kaons

Predictions for semi-leptonic decay rates of the \τ lepton into two meson final states K^- π^0 υ_τ, (K^0 ) ̅π^- υ_τ, K^0 K^- υ_τ, and three meson final states K^- π^- K^+ υ_τ, K^0 π^- 〖(K^0 ) ̅〗υ_τ, K_s π^- K_s υ_τ, K_s π^- K_L υ_τ, K_L π^- K_L υ_τ,K^- π^0 K^0 υ_τ,π^0 π^0 K^- υ_τ, K^- π^- π^+ υ_τ, π^- 〖(K^0 ) ̅π^0 v〗_τ are derived. The hadronic matrix elements are expressed in terms of form factors, which can be predicted by chiral Lagrangians supplemented by informations about all possible low-lying resonances in the different channels. Isospin symmetry relations among the different final states are carefully taken into account. The calculated branching ratios are compared with measured decay rates where data are available.