The Kπ vector form factor and constraints from K_l3 decays

The slope and curvature parameters of the Kπ vector form factor, F + Kπ, are fitted to the data on τ → Kπντ and Kl3 decays yielding λ′+ =(25.49 ± 0.31) × 10-3 and λ″+= (12.22 ± 0.14) × 10-4. The pole position of the K*(892)±is found to be at m K*(892)±= 892.0 ± 0.5 MeV and ΛK*(892)±= 46.5 ± 1.1 MeV. The phase-space integrals relevant for Kl3 analyses and the P-wave isospin-1/2 Kπ phase-shift threshold parameters are also calculated.