Thermodynamic consistency, quark mass scaling, and properties of strange matter

The previous thermodynamic treatment for models with density and/or temperature dependent quark masses is shown to be inconsistent with the requirement of fundamental thermodynamics. We therefore study a fully self-consistent one according to the fundamental differential equation of thermodynamics. After obtaining a new quark mass scaling with the inclusion of both confinement and leading-order perturbative interactions, we investigate properties of strange quark matter in the fully consistent thermodynamic treatment. It is found that the equation of state become stiffer, and accordingly, the maximum mass of strange stars is as large as about 2 times the solar mass, if strange quark matter is absolutely or metastable.

Charge, strangeness and radius of strangelets

We investigate, at both zero and finite temperature, the properties of strangelets versus the electric charge Z and strangeness S. The strangelet radius is not a monotonic function of either charge or strangeness, and a minimum is reached in the (Z, S) plane. However, the thermodynamically stable strangelets do not correspond to the radius minimum. The minimum radius always appears at positive strangeness, while the stable radius may appear at negative strangeness for very small baryon numbers. For large baryon numbers, the stable radius is proportional to the cubic root of baryon numbers, but inversely proportional to the square root of the confinement parameter in the present model. If bulk strange quark matter is absolutely stable, the reduced size of strangelets is about 1 fm, which may be relevant for the analysis of the strangelet production and detection.