Modifying operator product expansions by non-perturbative non-locality

Local quark-hadron duality violations in conventional applications of the o perator product expansion are proposed to have their origin in the fact tha t the QCD vacuum or a hadronic state is not only characterized by nonvanish ing expectation values of local, gauge invariant operators but also by fini te correlation lengths of the corresponding gauge invariant n-point functio ns. Utilizing high-resolution lattice information on these correlators a no n-perturbative component of OPE coarse graining is proposed which, in princ iple, allows for a determination of the critical dimension where the break- down of the expansion sets in. (C) 2001 Published by Elsevier Science B.V.