# Dynamical vs. equilibrium properties of the QCD phase transition: a holographic perspective

## TL;DR

This paper uses a holographic Einstein-Maxwell-Dilaton model to study how QCD phase transition properties depend on temperature and baryon chemical potential, revealing suppressed charge diffusion and varying viscosities in baryon-rich quark-gluon plasma.

## Contribution

It provides the first determination of transition temperatures for various quantities as functions of baryon chemical potential using a holographic model.

## Key findings

- Transition temperatures range from 130 to 200 MeV and decrease with increasing chemical potential.
- Charge diffusion and viscosities are suppressed in baryon-rich plasma.
- The crossover nature of the transition persists at large chemical potentials.

## Abstract

We employ an Einstein-Maxwell-Dilaton (EMD) holographic model, which is known to be in good agreement with lattice results for the QCD equation of state with $(2+1)$ flavors and physical quark masses, to investigate the temperature and baryon chemical potential dependence of the susceptibilities, conductivities, and diffusion coefficients associated with baryon, electric, and strangeness conserved charges. We also determine how the bulk and shear viscosities of the plasma vary in the plane of temperature and baryon chemical potential. The diffusion of conserved charges and the hydrodynamic viscosities in a baryon rich quark-gluon plasma are found to be suppressed with respect to the zero net baryon case. The transition temperatures associated with equilibrium and non-equilibrium quantities are determined as a function of the baryon chemical potential for the first time. Because of the crossover nature of the QCD phase transition even at moderately large values of the chemical potential, we find that the transition temperatures associated with different quantities are spread in the interval between $130-200$ MeV and they all decrease with increasing baryon chemical potential.