Calculation of kaon semileptonic form factor with the PACS10 configuration

TL;DR

This study computes kaon semileptonic form factors using large-volume lattice configurations at physical quark masses, extrapolating to the continuum and determining |V_{us}|, contributing to precision tests of the Standard Model.

Contribution

First lattice calculation of kaon semileptonic form factors using PACS10 configurations with physical volume and multiple lattice spacings, including continuum extrapolation.

Findings

Preliminary form factor results at two lattice spacings.

Continuum limit extrapolation using NLO SU(3) ChPT.

Estimated |V_{us}| consistent with CKM unitarity and recent lattice results.

Abstract

We present preliminary results for the kaon semileptonic form factors using the PACS10 configurations, whose physical volume is more than (10 fm)$^3$ at the physical point with the lattice spacings of 0.085 and 0.064 fm. The configurations were generated using the Iwasaki gauge action and $N_f=2+1$ stout-smeared Clover quark action. For the continuum extrapolation, we calculate the form factors with the local and conserved vector currents. The form factors in the two lattice spacings are extrapolated to the continuum limit using a fit function based on the NLO SU(3) ChPT formula with terms corresponding to finite lattice spacing effects. The value of $|V_{us}|$ is determined using our preliminary result of the form factor at the zero momentum transfer in the continuum limit. The result is compared with recent lattice results, and also predictions of the standard model from the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix.