Kl3 semileptonic form factor from 2+1 flavour lattice QCD

TL;DR

This paper reports the first lattice QCD calculations of the Kl3 form factor with 2+1 dynamical flavors, providing precise theoretical input that refines the determination of the CKM matrix element |V_{us}|.

Contribution

It introduces the first calculation of the Kl3 form factor using 2+1 flavor domain wall fermions, improving the precision of |V_{us}| extraction.

Findings

f_+(0)=0.964(5) from lattice QCD

|V_{us}|=0.2249(14) combining experimental data

O(p^6) correction =-0.013(5) in chiral expansion

Abstract

We present the first results for the Kl3 form factor from simulations with 2+1 flavours of dynamical domain wall quarks. Combining our result, namely f_+(0)=0.964(5), with the latest experimental results for Kl3 decays leads to |V_{us}|=0.2249(14), reducing the uncertaintity in this important parameter. For the O(p^6) term in the chiral expansion we obtain \Delta f=-0.013(5).