Determination of pion-baryon coupling constants from QCD sum rules

We evaluate the $\pi NN$, $\pi\Sigma\Sigma$ and $\pi\Sigma\Lambda$ coupling constants using QCD sum rules based on pion-to-vacuum matrix elements of correlators of two interpolating baryon fields. The parts of the correlators with Dirac structure $k\llap/\gamma_5$ are used, keeping all terms up to dimension 5 in the OPE and including continuum contributions on the phenomenological side. The ratios of these sum rules to baryon mass sum rules yield stable results with values for the couplings of $g_{\pi NN}=12\pm 5$, $g_{\pi\Sigma\Sigma}=9.5\pm 6.5$ and $g_{\pi\Sigma\Lambda}=4\pm 2$. The sources of uncertainty are discussed.