Color path-integral Monte-Carlo simulations of quark-gluon plasma: Thermodynamic and transport properties

TL;DR

This paper introduces a color quantum path-integral Monte-Carlo method for calculating thermodynamic and transport properties of the quark-gluon plasma, revealing its quantum liquid-like behavior and internal structure consistent with lattice QCD results.

Contribution

It develops a novel color PIMC and Wigner dynamics approach for QGP, providing new insights into its thermodynamics and transport properties, including the existence of gluon-gluon bound states.

Findings

QGP exhibits quantum liquid-like properties up to 525 MeV.

Gluon-gluon bound states (glueballs) are present above the phase transition.

Calculated shear viscosity aligns with experimental estimates.

Abstract

Based on the quasiparticle model of the quark-gluon plasma (QGP), a color quantum path-integral Monte-Carlo (PIMC) method for calculation of thermodynamic properties and -- closely related to the latter -- a Wigner dynamics method for calculation of transport properties of the QGP are formulated. The QGP partition function is presented in the form of a color path integral with a new relativistic measure instead of the Gaussian one traditionally used in the Feynman-Wiener path integral. It is shown that the PIMC method is able to reproduce the lattice QCD equation of state at zero baryon chemical potential at realistic model parameters (i.e. quasiparticle masses and coupling constant) and also yields valuable insight into the internal structure of the QGP. Our results indicate that the QGP reveals quantum liquid-like (rather than gas-like) properties up to the highest considered temperature of 525 MeV. The pair distribution functions clearly reflect the existence of gluon-gluon bound states, i.e. glueballs, at temperatures just above the phase transition, while meson-like $q\bar{q}$ bound states are not found. The calculated self-diffusion coefficient agrees well with some estimates of the heavy-quark diffusion constant available from recent lattice data and also with an analysis of heavy-quark quenching in experiments on ultrarelativistic heavy ion collisions, however, appreciably exceeds other estimates. The lattice and heavy-quark-quenching results on the heavy-quark diffusion are still rather diverse. The obtained results for the shear viscosity are in the range of those deduced from an analysis of the experimental elliptic flow in ultrarelativistic heavy ions collisions, i.e. in terms the viscosity-to-entropy ratio, $1/4\pi < \eta/S < 2.5/4\pi$, in the temperature range from 170 to 440 MeV.