Transport Properties of Quark–Gluon Plasmas

Abstract

Hydrodynamic simulations of relativistic heavy-ion collisions require knowledge, not only of the thermodynamic properties of the QGP, but also of the transport properties. While significant progress in calculations of the thermodynamic properties of QGP has been made in recent years, the transport properties are still poorly accessible using lattice QCD (Meyer 2007). It is therefore crucial to devise reliable and manageable theoretical tools for a quantitative description of non-Abelian QGP, both in and out of equilibrium. Unfortunately, the DPIMC method itself cannot directly predict transport properties. To simulate quantum QGP transport and thermodynamic properties in a unified approach, it is reasonable to combine the path integral and Wigner (in phase space) formulations of quantum mechanics. As will be shown below, to calculate kinetic coefficients according to the quantum Kubo formulas, the DPIMC method can be used to generate initial conditions (equilibrium quasiparticle configurations) for virtual dynamical Wigner trajectories in color phase space, describing the time evolution for space, momentum, and color variables. Correlation functions and kinetic coefficients are calculated as averages of Weyl’s symbols for dynamic quantum operators along these trajectories. The basic ideas of this approach have been published in (Filinov 2011). This method is applicable to systems with arbitrarily strong interactions. The self-diffusion coefficient and viscosity of the strongly coupled QGP have been calculated using this approach.