QCD sum rules for the nucleon and the non-locality of quark condensates
  We emphasize the role of the x dependence of the quark condensate <|\bar q(0)q(x)|> originated by the zero fermion modes in the instanton vacuum. The effect is not negligible since the inverse size of the instanton 1/\rho~600MeV is comparable with the value of Borel mass M~1GeV. Using as an example the sum rules for the nucleon we show that this "non-locality" may strongly affected the conventional results obtained under the <|\bar q(0)q(x)|>=<|\bar q(0)q(0)|> approximation. 
M. G. Ryskin, V. A. Sadovnikova
hep-ph