Strongly coupled plasma with electric and magnetic charges

TL;DR

This work reframes the finite-$T$ QCD medium as a strongly coupled plasma with coexisting electrically and magnetically charged quasiparticles (EQPs and MQPs). Using classical molecular dynamics for a 2E-2M plasma, it analyzes the equation of state, diffusion, viscosity, and conductivity, showing that increasing magnetic content can significantly reduce viscosity and alter transport near the sQGP regime. In the very strongly coupled regime, it identifies monopole, quadruple, and plasmon collective modes and demonstrates their clear connections to specific time-correlation functions, with system-size scaling consistent with sound-like propagation. A mapping to RHIC phenomenology and AdS/CFT results suggests that the EQP/MQP framework captures essential aspects of sQGP transport and collective behavior near $T_c$, offering a bridge between lattice insights, theory, and experiment.

Abstract

A number of theoretical and lattice results lead us to believe that Quark-Gluon Plasma not too far from $T_c$ contains not only electrically charged quasiparticles -- quarks and gluons -- but magnetically charged ones -- monopoles and dyons -- as well. Although binary systems like charge-monopole and charge-dyon were considered in details before in both classical and quantum settings, it is the first study of coexisting electric and magnetic particles in many-body context. We perform Molecular Dynamics study of strongly coupled plasmas with $\sim 1000$ particles and different fraction of magnetic charges. Correlation functions and Kubo formulae lead to such transport properties as diffusion constant, shear viscosity and electric conductivity: we compare the first two with empirical data from RHIC experiments as well as results from AdS/CFT correspondence. We also study a number of collective excitations in these systems.

Figures (32)

• Figure 1: (color online) A schematic phase diagram on a ("compactified") plane of temperature and baryonic chemical potential $T-\mu$. The (blue) shaded region shows "magnetically dominated" region $g<e$, which includes the e-confined hadronic phase as well as "postconfined" part of the QGP domain. Light region includes "electrically dominated" part of QGP and also color superconductivity (CS) region, which has e-charged diquark condensates and therefore obviously m-confined. The dashed line called "e=g line" is the line of electric-magnetic equilibrium. The solid lines indicate true phase transitions, while the dash-dotted line is a deconfinement cross-over line.
• Figure 2: The energy (a) and entropy (b) (as $TS_\infty(T)$) derived from the free energy of two static quarks separated by large distance, in $2$-flavor QCD according to Kaczmarek:2005zp.
• Figure 3: Temperature dependence of electric and magnetic screening masses according to Nakamura et al Nakamura:2003pu. The dotted line is fitted by the assumption, $m_g \sim g^2T$. For the electric mass, the dashed and solid lines represent LOP and HTL resummation results, respectively.
• Figure 4: The trajectory of a dyon in a field of static charge.
• Figure 5: Trajectory of monopole motion in a static electric dipole field (with charges at $\pm 1 \, \hat{z}$) as (left panel)projected on x-y plane and (right panel)projected on R-z plane ($R=\sqrt{x^2+y^2}$).