We evaluate the strangeness-conserving $N N$, $SigmaSigma$, $XiXi$, $LambdaSigma$ and the strangeness-changing $Lambda N$, $Sigma N$, $LambdaXi$, $SigmaXi$ axial charges in lattice QCD with two flavors of dynamical quarks and extend our previous work
on pseudoscalar-meson-octet-baryon coupling constants so as to include $piXiXi$, $KLambdaXi$ and $KSigmaXi$ coupling constants. We find that the axial charges have rather weak quark-mass dependence and the breaking in SU(3)-flavor symmetry is small at each quark-mass point we consider.
We evaluate the $pi N!N$, $piSigmaSigma$, $piLambdaSigma$, $KLambda N$ and $K 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 symmetr
y are computed at the point where the three quark flavors are degenerate at the physical $s$-quark mass. In particular, we obtain $alphaequiv F/(F+D)=0.395(6)$. 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.
