  We argue that the extended Nambu-Jona-Lasinio model of hadrons can be be
probed and constrained in a nontrivial way via QCD sum rules. While there arise
rather restrictive bounds on the strength of the effective four-fermion
interaction in the vector channel, introduction of the four-fermion interaction
in the pseudoscalar channel could resolve a long standing puzzle of QCD sum
rules. We speculate also on possible connection between effective four-quark
interactions describing the low-energy phenomenology and ultraviolet
renormalons of the fundamental QCD.

High Energy Physics - Phenomenology