Pseudoscalar-meson-octet-baryon coupling constants in two-flavor lattice QCD

Abstract

We evaluate the $\ensuremath{\pi}NN$, $\ensuremath{\pi}\ensuremath{\Sigma}\ensuremath{\Sigma}$, $\ensuremath{\pi}\ensuremath{\Lambda}\ensuremath{\Sigma}$, $K\ensuremath{\Lambda}N$ and $K\ensuremath{\Sigma}N$ coupling constants and the corresponding monopole masses in lattice QCD with two flavors of dynamical quarks. The parameters representing the SU(3)-flavor symmetry are computed at the point where the three quark flavors are degenerate at the physical $s$-quark mass. In particular, we obtain $\ensuremath{\alpha}\ensuremath{\equiv}F/(F+D)=0.395(6)$. The quark-mass dependences of the coupling constants are obtained by changing the $u$- and the $d$-quark masses. We find that the SU(3)-flavor parameters have weak quark-mass dependence and thus the SU(3)-flavor symmetry is broken by only a few percent at each quark-mass point we consider.