Generic framework for non-perturbative QCD in light hadrons

TL;DR

This paper introduces a systematic framework using the instanton liquid model to study non-perturbative QCD effects in light hadrons, aligning well with lattice QCD results and simplifying complex calculations.

Contribution

It develops a density expansion and diagrammatic rules within the instanton liquid model to compute vacuum and hadronic properties in QCD.

Findings

ILM predictions agree with lattice QCD results

Nonperturbative physics controlled by few parameters

Framework applicable to low-lying hadron physics

Abstract

This paper aims to serve as an introductory resource for disseminating the concept of instanton liquid model to individuals with interests in quantum chromodynamics (QCD) for hadrons. We discuss several topological aspects of the QCD vacuum and briefly review recent progress on this intuitive unifying framework for the lowlying hadron physics rooted in QCD by introducing the vacuum as a liquid of pseudoparticles. We develop systematic density expansion on the dilute vacuum with diagrammatical Feynman rules to calculate the vacuum expectation values (VEVs) and generalize the calculations to hadronic matrix element (charges), and hadronic form factors using the instanton liquid model (ILM). The ILM prediction are well-consistent with those of recent lattice QCD calculations. Thereby, the nonperturbative physics can be well-controlled by only a few parameters: instanton size $\rho$ and instanton density $n_{I+A}$, and current quark mass $m$.