In search of the QCD-Gravity correspondence

TL;DR

This paper explores dualities like AdS/CFT and effective low-energy theories to better understand non-perturbative QCD phenomena, especially in the context of heavy ion collisions and strongly-interacting matter.

Contribution

It introduces duality frameworks that connect QCD with string theories and curved gravitational backgrounds, aiming to address non-perturbative challenges.

Findings

Application of dualities to QCD transport properties

Insights into shear and bulk viscosities of QCD matter

Potential understanding of confinement and hadronization mechanisms

Abstract

Quantum Chromodynamics (QCD) is the fundamental theory of strong interactions. It describes the behavior of quarks and gluons which are the smallest known constituents of nuclear matter. The difficulties in solving the theory at low energies in the strongly interacting, non-perturbative regime have left unanswered many important questions in QCD, such as the nature of confinement or the mechanism of hadronization. In these lectures oriented towards the students we introduce two classes of dualities that attempt to reproduce many of the features of QCD, while making the treatment at strong coupling more tractable: (1) the AdS/CFT correspondence between a specific class of string theories and a conformal field theory and (2) an effective low-energy theory of QCD dual to classical QCD on a curved conformal gravitational background. The hope is that by applying these dualities to the evaluation of various properties of the strongly-interacting matter produced in heavy ion collisions one can understand how QCD behaves at strong coupling. We give an outline of the applications, with emphasis on two transport coefficients of QCD matter -- shear and bulk viscosities.