Diffusion coefficient matrix of the strongly interacting quark-gluon plasma

TL;DR

This paper calculates the diffusion coefficient matrix for baryon, strange, and electric charges in the strongly interacting quark-gluon plasma using non-perturbative models and compares two methods, providing insights for hydrodynamic simulations.

Contribution

It introduces a detailed evaluation of the diffusion coefficient matrix in sQGP using the DQPM and compares two computational methods, enhancing understanding of charge transport.

Findings

Good agreement with lattice QCD data for electric charge diffusion at zero baryon chemical potential.

Qualitative agreement with holographic predictions for all diagonal diffusion components.

Provides diffusion coefficients essential for improved hydrodynamic modeling of sQGP.

Abstract

We study the diffusion properties of the strongly interacting quark-gluon plasma (sQGP) and evaluate the diffusion coefficient matrix for the baryon ($B$), strange ($S$) and electric ($Q$) charges - $\kappa_{qq'}$ ($q,q' = B, S, Q$) and show their dependence on temperature $T$ and baryon chemical potential $\mu_B$. The non-perturbative nature of the sQGP is evaluated within the Dynamical Quasi-Particle Model (DQPM) which is matched to reproduce the equation of state of the partonic matter above the deconfinement temperature $T_c$ from lattice QCD. The calculation of diffusion coefficients is based on two methods: i) the Chapman-Enskog method for the linearized Boltzmann equation, which allows to explore non-equilibrium corrections for the phase-space distribution function in leading order of the Knudsen numbers as well as ii) the relaxation time approximation (RTA). In this work we explore the differences between the two methods. We find a good agreement with the available lattice QCD data in case of the electric charge diffusion coefficient (or electric conductivity) at vanishing baryon chemical potential as well as a qualitative agreement with the recent predictions from the holographic approach for all diagonal components of the diffusion coefficient matrix. The knowledge of the diffusion coefficient matrix is also of special interest for more accurate hydrodynamic simulations.