Dispersive representation of the scalar and vector Kpi form factors for tau --> K pi nu_tau and K_{l3} decays

TL;DR

This paper introduces a dispersive parametrization of Kpi form factors in tau and K_{l3} decays, enabling precise Standard Model tests and improved determination of fundamental parameters like |V_{us}|.

Contribution

It presents a novel dispersive approach to model Kpi form factors in tau and K_{l3} decays, enhancing the accuracy of Standard Model tests.

Findings

Precise determination of f_+(0)|V_{us}| from tau decays.

Comparison and combination of tau and K_{l3} decay analyses.

Improved constraints on Standard Model parameters.

Abstract

Recently, the tau --> K pi nu_tau decay spectrum has been measured by the Belle and BaBar collaborations. In this work, we present an analysis of such decays introducing a dispersive parametrization for the vector and scalar Kpi form factors. This allows for precise tests of the Standard Model. For instance, the determination of f_+(0)|V_{us}| from these decays is discussed. A comparison and a combination of these results with the analyses of the K_{l3} decays is also considered.