Hyperon-nucleon coupling from QCD sum rules

The NKY coupling constant for $Y = \Lambda$ and $\Sigma$ is evaluated in a QCD sum rule calculation. We discuss and extend the result of a previous analysis in the $\rlap{/}{q}i\gamma_5$ structure and compare it with the result obtained with the use of the $\gamma_5 \sigma_{\mu \nu}$ structure. We find a huge violation of the SU(3) symmetry in the $\gamma_5 \sigma_{\mu \nu}$ structure.