Dispersive representation of the K pi vector form factor and fits to tau -> K pi nu(tau) and Ke3 data

Abstract

Recently, we introduced several dispersive representations for the vector $K\pi$ form factor and fitted them to the Belle spectrum of $\tau \to K\pi {\nu }_{\tau }$. Here, we briefly present the model and discuss the results for the slope and curvature of $F_{+}(s)$ arising from the best fit. Furthermore, we compare the pole position of the charged $K^{\ast }(892)$ computed from our model with other results in the literature. Finally, we discuss the prospects of a simultaneous fit to $\tau \to K\pi {\nu }_{\tau }$ and $K_{e3}$ spectra.

Comments: Talk given at "International Workshop on Effective Field Theories: from the pion to the upsilon", February 2009, Valencia, Spain. 7 pages, 2 figures. PoS style. Minor correction in figure 2