Quark saturation in the QCD phase diagram

TL;DR

This paper investigates the conditions under which Quarkyonic Matter appears in the QCD phase diagram, focusing on the phase space density of quarks and the contributions of various hadrons at finite temperature.

Contribution

It introduces a model to estimate the onset of Quarkyonic Matter considering temperature effects and hadron contributions, providing new insights into the phase transition region.

Findings

The transition to Quarkyonic Matter occurs at phase space density of one.

Finite temperature allows excitation of all baryons and mesons, affecting quark density.

Predictions of a critical point near the intersection of deconfinement and Quarkyonic transition lines.

Abstract

We determine the onset of Quarkyonic Matter corresponding to values of temperature and baryon chemical potential at which the quark phase space density becomes one. At zero temperature for baryon chemical potentials below the mass of the Lambda baryon, only nucleons contribute to the quark density. This is different at finite temperature, where all baryons, mesons and their resonances can be excited and thus add quarks to the phase space. The probability density to find a quark inside a hadron is determined using the Yukawa ansatz of the IdylliQ model of Quarkyonic Matter. We estimate separately the magnitude of the various contributions of nucleons, Delta baryons, pions as well as further hadrons and resonances. The uncertainty in the parametrization of the probability density to find a quark inside a nucleon is spanned by assuming that at zero temperature the transition density to Quarkyonic Matter is between one and three times that of nuclear matter. Various predictions for a possible critical point associated with the chiral phase transition are found close to a triple point at which the line of the deconfinement transition and the curve associated with the transition to Quarkyonic Matter intersect. These considerations provide an estimate for the region in the QCD phase diagram where Quarkyonic Matter may be found.