Dispersive representation of the scalar and vector Kpi form factors for   tau --> K pi nu_tau and K_{l3} decays
  Recently, the tau --> K pi nu_tau decay spectrum has been measured by the Belle and BaBar collaborations. In this work, we present an analysis of such decays introducing a dispersive parametrization for the vector and scalar Kpi form factors. This allows for precise tests of the Standard Model. For instance, the determination of f_+(0)|V_{us}| from these decays is discussed. A comparison and a combination of these results with the analyses of the K_{l3} decays is also considered. 
V\'eronique Bernard, Diogo R. Boito and Emilie Passemar
hep-ph hep-ex