Quantum van der Waals theory meets quarkyonic matter

TL;DR

This paper develops a quantum van der Waals model for quarkyonic matter incorporating empirical nuclear properties, revealing a nuclear liquid-gas transition and a transition to quarkyonic matter at accessible densities, with implications for heavy-ion collisions.

Contribution

It introduces a quantum van der Waals framework for quarkyonic matter that aligns with empirical nuclear data and explores the baryquark matter scenario as an energetically favored alternative.

Findings

Identifies a nuclear liquid-gas transition at low densities.

Predicts a transition to quarkyonic matter at 1.5-2 times nuclear saturation density.

Shows the equation of state features a peak in sound velocity.

Abstract

We incorporate the empirical low-density properties of isospin symmetric nuclear matter into the excluded-volume model for quarkyonic matter by including attractive mean field in the nucleonic sector and considering variations on the nucleon excluded volume mechanism. This corresponds to the quantum van der Waals equation for nucleons, with the interaction parameters fixed to empirical ground state properties of nuclear matter. The resulting equation of state exhibits the nuclear liquid-gas transition at $n_B \leq \rho_0$ and undergoes a transition to quarkyonic matter at densities $n_B \sim 1.5-2 \rho_0$ that are reachable in intermediate energy heavy-ion collisions. The transition is accompanied by a peak in the sound velocity. The results depend only mildly on the chosen excluded volume mechanism but do require the introduction of an infrared regulator $\Lambda$ to avoid the acausal sound velocity. We also consider the recently proposed baryquark matter scenario for the realization of the Pauli exclusion principle, which yields a similar equation of state and turns out to be energetically favored in all the considered setups.