Hyperon vector form factor from2+1flavor lattice QCD

Abstract

We present the first result for the hyperon vector form factor ${f}_{1}$ for ${\ensuremath{\Xi}}^{0}\ensuremath{\rightarrow}{\ensuremath{\Sigma}}^{+}l\overline{\ensuremath{\nu}}$ and ${\ensuremath{\Sigma}}^{\ensuremath{-}}\ensuremath{\rightarrow}nl\overline{\ensuremath{\nu}}$ 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 $\ensuremath{\beta}=2.13$, corresponding to a cutoff ${a}^{\ensuremath{-}1}=1.73\text{ }\text{ }\mathrm{GeV}$. 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.