τ^- →K^- η ^(')ν<inf>τ</inf> decays in Chiral Perturbation Theory with resonances

We have studied the τ- → K-η(') ντ decays within Chiral Perturbation Theory including resonances as explicit degrees of freedom. We have considered three different form factors according to treatment of final-state interactions. In increasing degree of soundness: Breit-Wigner, exponential resummation and dispersive representation. We find that although the first one fails in accounting for the data on the Kη mode, the other two approaches provide good fits to them which are sensitive to the K*(1410) pole parameters, that are determined to be Mk*' = (1330+27-41) MeV and Γk*' = (217+68-122) MeV. These values are competitive with the standard determination from τ- → (Kπ)-ντ decays. The corresponding predictions for the π-→ K-η'ντ channel respect the current upper bound and hint to the discovery of this decay mode in the near future. © SISSA 2013.