QCD correlation functions and instantons

TL;DR

This paper reviews how QCD correlation functions at intermediate distances reveal that instanton-induced forces are dominant in light quark physics, supported by experimental, instanton liquid, and lattice studies, and discusses chiral symmetry restoration via instanton molecules.

Contribution

It synthesizes recent findings from experiments, instanton liquid models, and lattice QCD, highlighting the role of instantons in light quark interactions and chiral symmetry restoration.

Findings

Instanton-induced forces dominate light quark physics.

Agreement among experimental, instanton liquid, and lattice studies.

Chiral symmetry restoration linked to instanton molecule formation.

Abstract

QCD point-to-point correlation functions at distances .2-1 fm are very different for different channels, and they tell us a lot about inter-quark interactions. Recent studies based on experimental data, 'instanton liquid' approach and lattice measurements are reviewed. Agreement between all of them show that instanton-induced forces dominate the light quark physics, and new findings by Negele et al, that {\it hadrons survive 'cooling'}, make this statement obvious. We also argue that {\it chiral symmetery restoration} is due to breaking of the 'instanton liquid' into {\it polarized} 'instanton molecules'. % For Lattice-93 proceedings, figures and % hard copies available at request, sorry.