Mixed Quark-Gluon Condensate Beyond Chiral Limit

Abstract

Using the Dyson–Schwinger equation and perturbation theory, we calculate the mixed quark-gluon condensates in the chiral limit and in the case of nonzero quark current mass for the light quark u/d and strange quark s. The results show that the mixed quark-gluon condensate will decrease when the quark mass increases. For the quark with zero mass, we obtain m20 = g⟨q̄σμν Gμνq⟩/⟨q̄q⟩ ≅ 0.68 GeV2, which is in good agreement with the QCD sum rules estimate m20 = (0.8 ± 0.2) GeV2.