Determination of pion-baryon coupling constants from QCD sum rules

We evaluate the πNN, πΣΣ, and πΣΛ 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/${\gamma }_5$ 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 ${\mathit{g}}_{\mathrm{\pi }\mathit{NN}}$=12±5, ${\mathit{g}}_{\mathrm{\pi }\mathrm{\Sigma }\mathrm{\Sigma }}$=7±4, and ${\mathit{g}}_{\mathrm{\pi }\mathrm{\Sigma }\mathrm{\Lambda }}$=6±3. The sources of uncertainty are discussed. © 1996 The American Physical Society.