The Kpi vector form factor and constraints from Kl3 decays

Abstract

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 ${\lambda }_{+}^{\prime }=(25.49\pm 0.31)\times 10^{-3}$ and ${\lambda }_{+}"=(12.22\pm 0.14)\times 10^{-4}$. The pole position of the $K^{\ast }(892{)}^{\pm }$ is found to be at $m_{K^{\ast }(892{)}^{\pm }}=892.0\pm 0.5$ MeV and ${\Gamma }_{K^{\ast }(892{)}^{\pm }}=46.5\pm 1.1$ MeV. The phase-space integrals relevant for $K_{l3}$ analyses and the $P$-wave isospin-1/2 $K\pi$ phase-shift threshold parameters are also calculated.

Comments: 6 pages, uses econfmacros style. Talk presented by R. Escribano at the 6th International Workshop on the CKM Unitarity Triangle (CKM2010), University of Warwick, UK, 6-10 September 2010