Snapshots of Hadrons, or the Story of How the Vacuum Medium Determines the Properties of the Classical Mesons Which Are Produced, Live and Die in the QCD Vacuum

TL;DR

This paper reviews the role of the QCD vacuum in determining meson properties, discussing sum rules, condensates, and recent developments in the context of quantum chromodynamics.

Contribution

It provides a comprehensive overview of QCD sum rules, vacuum condensates, and new theoretical methods for understanding hadron properties influenced by the QCD vacuum.

Findings

QCD vacuum significantly affects meson characteristics.

Introduction of light-cone and heavy flavor sum rules.

Insights into lattice QCD and vacuum fluctuations.

Abstract

1. QCD Sum Rules: 20 Years After; 2. QCD Vacuum and Basics of the SVZ Method: 2.1 General ideas; 2.2. Getting started/Playing with toy models; 3. Vacuum Condensates; 4. Rho Meson in QCD; 5. Basic Theoretical Instrument -- Wilson's OPE; 6. Practical Version of OPE; 7. Low Energy Theorems; 8. Are All Hadrons Alike? 9. Ecological Niche; 10. New Developments: 10.1 Light-cone sum rules; 10.2 Heavy flavor sum rules; 11. Sum Rules and Lattices; 12. Vacuum Fluctuations are Subtle Creatures; 13. Instead of Conclusions.