G. X. Peng

Thermodynamics, strange quark matter, and strange stars

Upon application of both the general ensemble theory and basic thermodynamical principles, we derive in detail the thermodynamics of strange matter with density-dependent particle masses, which resolves the problem of inconsistencies in the thermodynamical properties of the earlier approaches. We then recalculate the properties of strange quark matter with this new thermodynamical treatment and our recently determined quark mass scaling, and find that the density behavior of the sound velocity is opposite to the previous finding, but consistent with one of our recent publications. The structure equations for strange stars are integrated with the presently obtained equation of state. We find that the mass-radius relation is similar to previous results except the maximum mass is smaller in our case if strange quark matter is absolutely stable.

Strange matter and strange stars in a thermodynamically self-consistent perturbation model with running coupling and running strange quark mass

A quark model with running coupling and running strange quark mass, which is thermodynamically self-consistent at both high and lower densities, is presented and applied to study properties of strange quark matter and structure of compact stars. An additional term to the thermodynamic potential density is determined by meeting the fundamental differential equation of thermodynamics. It plays an important role in comparatively lower density and ignorable at extremely high density, acting as a chemical-potential dependent bag constant. In this thermodynamically enhanced perturbative QCD model, strange quark matter still has the possibility of being absolutely stable, while the pure quark star has a sharp surface with a maximum mass as large as about 2 times the solar mass and a maximum radius of about 11 kilometers.

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.

New solutions for the color–flavor locked strangelets

Abstract Recent publications rule out the negatively charged beta equilibrium strangelets in ordinary phase, and the color–flavor locked (CFL) strangelets are reported to be also positively charged. This Letter presents new solutions to the system equations where CFL strangelets are slightly negatively charged. If the ratio of the square-root bag constant to the gap parameter is smaller than 170 MeV, the CFL strangelets are more stable than iron and the normal unpaired strangelets. For the same parameters, however, the positively charged CFL strangelets are more stable.

Charge, strangeness and radius of strangelets

We investigate, at both zero and finite temperatures, 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.

Quark matter in a parallel electric and magnetic field background: Chiral phase transition and equilibration of chiral density

In this article we study spontaneous chiral symmetry breaking for quark matter in the background of static and homogeneous parallel electric field

Renormalization group dependence of the QCD coupling

\bm E

Magnetized strange quark matter in a mass-density-dependent model

and magnetic field

Critical Temperature of Chiral Symmetry Restoration for Quark Matter with a Chiral Chemical Potential

\bm B

Strange quark matter and strangelets in the quasiparticle model

. We use a Nambu-Jona-Lasinio model with a local kernel interaction to compute the relevant quantities to describe chiral symmetry breaking at finite temperature for a wide range of