Strangelets at finite temperature

TL;DR

This paper investigates how the properties of strangelets change with temperature, revealing that surface tension increases with temperature and shell effects weaken, providing insights relevant to astrophysical and heavy-ion collision phenomena.

Contribution

It introduces a finite-temperature model for strangelets incorporating shell effects, surface tension, and emission rates, highlighting non-intuitive temperature dependencies of these properties.

Findings

Surface tension peaks at T ≈ 20-40 MeV.

Shell effects weaken with increasing temperature.

Emission rates vary with temperature and stability.

Abstract

We study the properties of strangelets at finite temperature $T$, employing an equivparticle model that incorporates both linear confinement and leading-order perturbative interactions with density-dependent quark masses. The shell effects are analyzed by solving the Dirac equations for quarks within the mean-field approximation. As temperature increases, these effects weaken due to the occupation probability of single-particle levels being governed by the Fermi-Dirac statistics, a phenomenon known as shell dampening. Surprisingly, the surface tension, derived from a liquid-drop formula, does not decrease with temperature but instead rises until it peaks at $T \approx 20-40$ MeV. At this temperature, shell corrections become negligible, and the formula provides a reasonable approximation for the free energy per baryon of strangelets. However, the curvature term decreases with $T$ despite the presence of shell effects. The neutron and proton emission rates are determined microscopically by the external nucleon gas densities that are in equilibrium with strangelets. These emission rate generally increases with $T$ for stable strangelets, but decrease for those that are unstable to nucleon emission at $T$ = 0. The other properties of $\beta$-stable strangelets obtained with various parameter sets are presented as well. The results indicated in this work are useful for understanding the products of binary compact star mergers and heavy-ion collisions.