The Kpi vector form factor and constraints from Kl3 decays

The slope and curvature parameters of the $K\pi$ vector form factor, $F_{+}^{K\pi }$, are fitted to the data on $\text{tauKpi}$ and $K_{l3}$ decays yielding ${\lambda }_{+}^{\mathrm{\prime }}=(25.49\pm 0.31)\times {10}^{-3}$ and $\lambda_+"= (12.22 \pm 0.14) \times 10^{-4}$\mathrm{.}Thepolepositionofthe$K^(892)^\pm$isfoundtobeat$m_{K^(892)^\pm}= 892.0\pm 0.5$MeVand$\Gamma_{K^*(892)^\pm}= 46.5 \pm1.1$MeV\mathrm{.}Thephase-spaceintegralsrelevantfor$K_{l3}$analysesandthe$P$-wave isospin-1/2 $K\pi$ phase-shift threshold parameters are also calculated.