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

TL;DR

This paper develops dispersive models for the K pi vector form factor, fitting them to tau decay data, and analyzes the form factor's properties, pole positions, and potential combined fits with K_{e3} data.

Contribution

It introduces dispersive representations for the K pi vector form factor and applies them to tau decay spectra, providing new insights into form factor parameters and resonance properties.

Findings

Determined the slope and curvature of the form factor from the fit.

Compared the K^*(892) pole position with other literature results.

Discussed the feasibility of combined fits to tau decay and K_{e3} 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 $K^*(892)$ 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.