E.G. Drukarev (PNPI), V.A. Sadovnikova (PNPI), M.G. Ryskin (PNPI)

QCD sum rules and the structure of the quark condensates

We emphasize the role of the detail structure of the quark condensates, that is the x-dependence of <|\bar{q}(x)q(0)|> vacuum expectation and the spin structure of the 4-quark condensate, for the QCD sum rules for the nucleon. We compare the results obtained under the usual OPE approach and that in the instanton vacuum model, where the quark condensates are formed by the zero fermion modes around the instanton.