Instanton liquid framework for non-perturbative QCD in light hadrons

In this paper, we review several topological aspects of the QCD vacuum and recent progress on this quantitative framework for the low-lying hadron physics rooted in QCD by introducing the vacuum as a liquid of pseudoparticles. We have developed systematic density expansion on the dilute vacuum to calculate the vacuum expectation values (VEVs) and generalize the calculations to hadronic matrix element and hadronic form factors using the instanton liquid model (ILM). Thereby, the nonperturbative physics can be analyzed in a systematic framework with a few parameters: instanton size ρ and instanton density n I + A , and current quark mass m .