Nonlocal gluon condensates in QCD sum rules

Nonlocal gluon condensates are vacuum expectations of the product field strength tensors. Short-distance expansions two-, three-, and four-gluon presented up to dimension-eight local operators. We propose a method for calculating Wilson coefficients based on Feynman diagram technique in background approach. The is demonstrated using glueball current correlators as examples. Methodological aspects approach discussed relation studies within QCD sum rules. confirm results operator expansion two-gluon ${0}^{\ifmmode\pm\else\textpm\fi{}+}$ calculate additional contributions coming from dimension-six four-quark condensate mixed quark-gluon condensates. used rules three-gluon glueballs revisited order.