Isospin dependence of the critical quark-deconfinement densities

TL;DR

This paper investigates how the ratio of protons to total nucleons ($Z/A$) affects the density at which hadronic matter transitions to quark matter, using different models and suggesting experimental tests for quark matter stability.

Contribution

It demonstrates the strong dependence of the critical deconfinement density on $Z/A$ and proposes experimental verification of quark matter stability in neutron-rich nuclei.

Findings

Critical density drops significantly for $Z/A$ around 0.3-0.4.

Critical density near nuclear saturation density for $Z/A \,\sim\, 0.3$.

Potential to test quark matter stability experimentally.

Abstract

We explore the dependence of the critical density, separating hadronic matter from a mixed phase of quarks and hadrons, on the ratio $Z/A$. We use both the MIT bag model and the Color Dielectric Model to describe the quark dynamics, while for the hadronic phase we employ various relativistic equations of state. We find that, if the parameters of quark models are fixed so that the existence of quark stars is allowed, then the critical density drops dramatically in the range $Z/A \sim $ 0.3--0.4. Moreover, for $Z/A \sim $ 0.3 the critical density is only slightly larger than the saturation density of symmetric nuclear-matter. This opens the possibility to verify the Witten-Bodmer hypothesis on absolute stability of quark matter using ground-based experiments in which neutron-rich nuclei are tested.