A New Model of Holographic QCD and Chiral Condensate in Dense Matter

TL;DR

This paper introduces a holographic QCD model incorporating asymptotic freedom and gluon condensation, analyzing how the chiral condensate varies with density in different phases, revealing a monotonical decrease at high densities.

Contribution

It presents a novel holographic QCD model with specific background branes and studies the density dependence of the chiral condensate using worldsheet instantons.

Findings

Chiral condensate decreases with density in the deconfined phase.

In the confined phase, condensate behavior varies, decreasing at high density and increasing at very low density.

The model aligns with theoretical expectations at high densities.

Abstract

We consider the model of holographic QCD with asymptotic freedom and gluon condensation in its vacuum. It consists of the color D4-branes and D0-branes as a background and the flavor D8-branes as a probe. By taking a specific field theory limit, the effective coupling decreases to vanish in UV region. We then introduce the uniformly distributed baryons in terms of the baryon vertices and study the density dependence of chiral condensate, which is evaluated using the worldsheet instanton method. In the confined phase, the chiral condensate as a function of density monotonically decreases in high baryon density. Such behavior is in agreement with the expectation, while in extremely low density it increases. We attribute this anomaly to the incorrect approximation of uniformity in very low density. In the deconfined phase the chiral condensate monotonically decreases in the whole region of density.