Holographic QCD with Dynamical Flavors

TL;DR

This paper presents analytic gravity solutions for a holographic QCD model with dynamical flavors, analyzing its phase diagram, thermodynamics, and vacuum properties in both confined and deconfined phases, with relevance to lattice QCD results.

Contribution

It provides the first analytic gravity solutions for the Witten-Sakai-Sugimoto model with dynamical flavors in the Veneziano limit, including holographic renormalization procedures.

Findings

Phase diagram at finite temperature and chemical potential resembles lattice QCD.

Flavor contributions significantly affect vacuum and thermodynamic properties.

Analytic solutions enable detailed study of confined and deconfined phases.

Abstract

Gravity solutions describing the Witten-Sakai-Sugimoto model of holographic QCD with dynamical flavors are presented. The field theory is studied in the Veneziano limit, at first order in the ratio of the number of flavors and colors. The gravity solutions are analytic and dual to the field theory either in the confined, low temperature phase or in the deconfined, high temperature phase with small baryonic charge density. The phase diagram and the flavor contributions to vacuum (e.g. string tension and hadron masses) and thermodynamical properties of the dual field theory are then deduced. The phase diagram of the model at finite temperature and imaginary chemical potential, as well as that of the unflavored theory at finite theta angle are also discussed in turn, showing qualitative similarities with recent lattice studies. Interesting degrees of freedom in each phase are discussed. Covariant counterterms for the Witten-Sakai-Sugimoto model are provided both in the probe approximation and in the backreacted case, allowing for a standard holographic renormalization of the theory.