Hyperon vector form factor from 2+1 flavor lattice QCD

TL;DR

This study provides the first lattice QCD calculation of the hyperon vector form factor for specific semileptonic decays, revealing a negative second-order SU(3) breaking correction that challenges existing theoretical predictions.

Contribution

It presents the inaugural fully dynamical lattice QCD results for the hyperon vector form factor f_1, including at lighter quark masses, and investigates SU(3) breaking effects.

Findings

Second-order SU(3) breaking correction to f_1(0) is negative.

Results disagree with baryon chiral perturbation theory predictions.

Results challenge large N_c analysis conclusions.

Abstract

We present the first result for the hyperon vector form factor f_1 for Xi^0 -> Sigma^+ l bar{nu} and Sigma^- -> n l bar{nu} semileptonic decays from fully dynamical lattice QCD. The calculations are carried out with gauge configurations generated by the RBC and UKQCD collaborations with (2+1)-flavors of dynamical domain-wall fermions and the Iwasaki gauge action at beta=2.13, corresponding to a cutoff 1/a=1.73 GeV. Our results, which are calculated at the lighter three sea quark masses (the lightest pion mass down to approximately 330 MeV), show that a sign of the second-order correction of SU(3) breaking on the hyperon vector coupling f_1(0) is negative. The tendency of the SU(3) breaking correction observed in this work disagrees with predictions of both the latest baryon chiral perturbation theory result and large N_c analysis.