Isospin breaking in diagonal pion-nucleon coupling constant: QCD sum rule approach

摘要

Using the vacuum-to-pion matrix element of the correlation function of the interpolating fields of two nucleons, isospin splitting in the diagonal pion-nucleon coupling constant has been studied in the framework of the conventional QCD sum rule. The quark mass dependent terms, pi(0)-eta mixing and electromagnetic corrections to meson-quark vertices have been included as well. Some of the implications of the isospin splitting have also been discussed.