Equation of State in a Strongly Interacting Relativistic System

TL;DR

This paper investigates how diquark interactions influence the equation of state in a strongly interacting quark system, highlighting the importance of diquark-diquark repulsion to prevent collapse and maintain a stable, BCS-like phase.

Contribution

It introduces a self-consistent treatment of diquark-diquark repulsion, showing its critical role in stabilizing the equation of state in strongly interacting quark matter.

Findings

Diquark-diquark repulsion prevents collapse into a pressureless state.

A critical coupling constant λ_C=7.65 marks the transition to positive pressure.

The system remains in a BCS-like phase throughout the strong interaction regime.

Abstract

We study the evolution of the equation of state of a strongly interacting quark system as a function of the diquark interaction strength. We show that for the system to avoid collapsing into a pressureless Boson gas at sufficiently strong diquark coupling strength, the diquark-diquark repulsion has to be self-consistently taken into account. In particular, we find that the tendency at zero temperature of the strongly interacting diquark gas to condense into the system ground state is compensated by the repulsion between diquarks if the diquark-diquark coupling constant is higher than a critical value $\lambda_C=7.65$. Considering such diquark-diquark repulsion, a positive pressure with no significant variation along the whole strongly interacting region is obtained. A consequence of the diquark-diquark repulsion is that the system maintains its BCS character in the whole strongly interacting region.