2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/45199We 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.LaTeX, 18 pages, UM-TH-94-19, DPNU-94-19High Energy Physics - Phenomenologytext