Lattice-QCD Determination of the Hyperon Axial Couplings in the Continuum Limit

Abstract

We present the first continuum extrapolation of the hyperon octet axial couplings ($g_{\Sigma \Sigma }$ and $g_{\Xi \Xi }$) from $N_f=2+1+1$ lattice QCD. These couplings are important parameters in the low-energy effective field theory description of the octet baryons and fundamental to the nonleptonic decays of hyperons and to hyperon-hyperon and hyperon-nucleon scattering with application to neutron stars. We use clover lattice fermion action for the valence quarks with sea quarks coming from configurations of $N_f=2+1+1$ highly improved staggered quarks (HISQ) generated by MILC Collaboration. Our work includes the first calculation of $g_{\Sigma \Sigma }$ and $g_{\Xi \Xi }$ directly at the physical pion mass on the lattice, and a full account of systematic uncertainty, including excited-state contamination, finite-volume effects and continuum extrapolation, all addressed for the first time. We find the continuum-limit hyperon coupling constants to be $g_{\Sigma \Sigma }=0.4455(55{)}_{\text{stat}}(65{)}_{\text{sys}}$ and $g_{\Xi \Xi }=-0.2703(47{)}_{\text{stat}}(13{)}_{\text{sys}}$, which correspond to low-energy constants of $D=0.708(10{)}_{\text{stat}}(6{)}_{\text{sys}}$ and $F=0.438(7{)}_{\text{stat}}(6{)}_{\text{sys}}$. The corresponding SU(3) symmetry breaking is 9\% which is about a factor of 2 smaller than the earlier lattice estimate.

Comments: 5 pages, 3 figures