Gluon condensates in a cold quark gluon plasma

TL;DR

This paper investigates the role of gluon condensates in a cold, high-density quark-gluon plasma, deriving an analytical equation of state that highlights the impact of non-perturbative effects on the system's properties.

Contribution

It introduces a mean field approach to incorporate gluon condensates into the equation of state for cold quark-gluon plasma, extending understanding beyond the MIT bag model.

Findings

Gluon condensates soften the equation of state.

Hard gluons increase energy density and pressure.

Analytical expression for the EOS derived from QCD Lagrangian.

Abstract

The quark gluon plasma which has been observed at RHIC is a strongly interacting system and has been called sQGP. This is a system at high temperatures and almost zero baryon chemical potential. A similar system with high chemical potential and almost zero temperature may exist in the core of compact stars. Most likely it is also a strongly interacting system. The strong interactions may be partly due to non-perturbative effects, which survive after the deconfinement transition and which can be related with the non-vanishing gluon condensates in the sQGP. In this work, starting from the QCD Lagrangian we perform a gluon field decomposition in low ("soft") and high ("hard") momentum components, we make a mean field approximation for the hard gluons and take the matrix elements of the soft gluon fields in the plasma. The latter are related to the condensates of dimension two and four. With these approximations we derive an analytical expression for the equation of state, which is compared to the MIT bag model one. The effect of the condensates is to soften the equation of state whereas the hard gluons significantly increase the energy density and the pressure.