Non-congruence of liquid-gas phase transition of asymmetric nuclear matter

TL;DR

This paper investigates the non-congruent liquid-gas phase transition in asymmetric nuclear matter, highlighting the effects of symmetry energy, Coulomb interaction, and temperature on phase structures and coexistence.

Contribution

It provides a detailed analysis of non-congruent phase transitions in asymmetric nuclear matter, including the impact of surface tension, Coulomb forces, and thermal effects on pasta structures.

Findings

Non-congruence occurs in asymmetric nuclear matter due to symmetry energy.

Coulomb interaction and surface tension significantly influence pasta structures.

Thermal effects alter the stability and configuration of mixed phases.

Abstract

We first explore the liquid-gas mixed phase in a bulk calculation, where two phases coexist without the geometrical structures. In the case of symmetric nuclear matter, the system behaves congruently, and the Maxwell construction becomes relevant. For asymmetric nuclear matter, on the other hand, the phase equilibrium is no more attained by the Maxwell construction since the liquid and gas phases are non-congruent; the particle fractions become completely different with each other. One of the origins of such non-congruence is attributed to the large symmetry energy. Subsequently we explore the charge-neutral nuclear matter with electrons by fully applying the Gibbs conditions to figure out the geometrical (pasta) structures in the liquid-gas mixed phase. We emphasize the effects of the surface tension and the Coulomb interaction on the pasta structures. We also discuss the thermal effects on the pasta structures.