Magnetic Component of Quark-Gluon Plasma is also a Liquid!

TL;DR

This paper investigates the magnetic component of quark-gluon plasma, showing it remains strongly coupled and liquid-like near the critical temperature, supported by simulations and lattice results, with implications for understanding QGP viscosity.

Contribution

It provides new simulation results on monopole correlations in QGP, confirming the magnetic coupling remains strong near T_c and supports the magnetic liquid scenario.

Findings

Magnetic Coulomb coupling increases as temperature approaches T_c.

Monopole correlations agree with recent lattice results.

Magnetic objects form a low-viscosity liquid near T_c.

Abstract

The so called magnetic scenario recently suggested in \cite{Liao_ES_mono} emphasizes the role of monopoles in strongly coupled quark-gluon plasma (sQGP) near/above the deconfinement temperature, and specifically predicts that they help reduce its viscosity by the so called "magnetic bottle" effect. Arguments for "magnetic liquid" in 1-2$T_c$ based on lattice measurement of monopole density were provided in \cite{Chernodub}. Here we present results for monopole-(anti)monopole correlation functions from the same classical molecular dynamics simulations, which are found to be in very good agreement with recent lattice results \cite{D'Alessandro:2007su}. We show that the magnetic Coulomb coupling does run in the direction $opposite$ to the electric one, as expected, and it is roughly inverse of the asymptotic freedom formula for the electric one. However, as $T$ decreases to $T_c$, the magnetic coupling never gets weak, with the plasma parameter always large enough ($\Gamma>1$). This nicely agrees with empirical evidences from RHIC experiments, implying that magnetic objects cannot have large mean free path and should also form a good liquid with low viscosity.