Gluons, Light and Heavy Quarks in the Instanton Vacuum

TL;DR

This paper reviews how instanton effects influence the properties of hadrons with light and heavy quarks, analyzing gluonic and quark correlators, and their impact on spectra and transitions within the Instanton Liquid Model of QCD.

Contribution

It provides a comprehensive analysis of nonperturbative instanton effects on heavy-light and heavy-heavy quark systems, including potential models and phenomenological implications.

Findings

Instanton effects contribute significantly to heavy quarkonium spectra.

Screening of one-gluon exchange at large distances due to instantons.

Instanton-induced modifications improve phenomenological potential models.

Abstract

In this review we will concentrate on the nonperturbative effects in the properties of hadrons made from the light-heavy and heavy-heavy quarks in the framework of Instanton Liquid Model (ILM) of QCD vacuum. We briefly discuss the main features of ILM and its applicability in the heavy quark sector. The properties of gluonic systems, light and heavy quark correlators in the instanton background are also analyzed. Consideration of the both, perturbative and nonperturbative, gluon effects in the instanton background for the single heavy quark will lead to the mass shift due to the direct-instanton nonperturbative and ILM modified perturbative contributions, respectively. For the interacting heavy quark-antiquarks, the potential consists the direct instanton induced part and the one-gluon exchange (OGE) perturbative part. OGE interactions are screened at large distances due to the nonperturbative dynamics. We discuss the estimations of instanton contributions in the phenomenological Cornell type potential model. As related to the experimental data we discuss the charmonium properties and the role of instanton effects in their spectra and transitions. We discuss also the main features of heavy-light quarks systems in the ILM. As an example, it is considering the process of pions emission by exited heavy quarkonium states.