Thermal entropy of a quark-antiquark pair above and below deconfinement from a dynamical holographic QCD model

TL;DR

This paper investigates the thermal entropy of a quark-antiquark pair across the deconfinement transition using a novel holographic QCD model that captures confinement, deconfinement, and finite temperature effects, aligning with lattice QCD results.

Contribution

It introduces a new holographic model that accurately mimics QCD phases and includes temperature and chemical potential effects, providing insights into entropy behavior near deconfinement.

Findings

Entropy peaks near the critical temperature T_c from both sides.

The model shows a non-vanishing string tension at T_c, consistent with lattice QCD.

Including chemical potential confirms the entropic behavior and affects the speed of sound.

Abstract

We discuss the entropy carried by a quark-antiquark pair, in particular across the deconfinement transition. We therefore rely on a self-consistent solution to Einstein-Maxwell-dilaton gravity, capable of mimicking essential features of QCD. In particular we introduce a novel model that still captures well the QCD confinement and deconfinement phases, while allowing the introduction of a temperature in a phase which resembles the confined phase, this thanks to it being dual to a small black hole. We pay due attention to some subtleties of such model. We confirm the lattice picture of a strong build-up of thermal entropy towards the critical temperature T_c, both coming from below or above T_c. We also include a chemical potential, confirming this entropic picture and we consider its effect on the speed of sound. Moreover, the temperature dependent confinement phase from the holography side allows us to find a string tension that does not vanish at T_c, a finding also supported by lattice QCD.