Phase diagram determination at fivefold nuclear compression

TL;DR

This paper identifies the conditions for the hadron-quark phase transition at fivefold nuclear compression, using simulations and experimental data, with implications for understanding the early universe and neutron star physics.

Contribution

It provides the first estimate of the onset of deconfinement at five times nuclear compression based on model simulations and experimental data comparison.

Findings

Deconfinement occurs at about five times nuclear compression.

Transition temperature is approximately 112 MeV.

Baryon chemical potential at transition is around 586 MeV.

Abstract

In the standard model of particle physics, the strong force is characterized by the theory of quantum chromodynamics (QCD). It is commonly understood from QCD properties that hadrons, at sufficiently high temperatures or densities, melt into their constituent quarks, thereby undergoing a deconfinement transition to a new phase of quarks and gluons, often referred to as quark matter or quark-gluon plasma (QGP) \cite{qcd00,qcd01}. Although QGP has been observed in relativistic heavy-ion collisions \cite{qgp1,qgp2}, uncertainties remain about when the onset of deconfinement occurs. After comparing simulations from a reliable hadron and quark relativistic transport model with recent data from the STAR experiment, we determined that the onset of the hadron-quark phase transition occurs at about five times nuclear compression, corresponding to temperature $T\sim$ 112 MeV and baryon chemical potential $\mu_{B}\sim$ 586 MeV, in the nuclear matter phase diagram. This discovery has significant implications for the studies of both the early and present universe \cite{ann2006}, including the fraction of dark matter formed in the early universe \cite{bhd2016,bhf1997,pbh20} and the structure and dynamics of neutron stars and their mergers \cite{nature2020}.