We analyze and quantify how the color-flavor locked (CFL) phase in dense matter enhances the parameter space for absolute stability (strange matter). We find that the “CFL strange matter” phase can be the true ground state of hadronic matter for a much wider range of the parameters of the model (the gap of the QCD Cooper pairs $\Delta ,$ the strange quark mass $m_s,$ and the bag constant $B)$ than the state without any pairing, and derive a full equation of state and an accurate analytic approximation to the lowest order in $\Delta$ and $m_s$ which may be directly used for applications. The effects of pairing on the equation of state are found to be small (as previously expected), but not negligible, and may be relevant for astrophysics.

We study the properties and stability of strange matter at T=0 in the quark mass-density-dependent model for noninteracting quarks. We found a wide ‘‘stability window’’ for the values of the parameters (C,${\mathit{M}}_{\mathit{s}0}$) and the resulting equation of state at low densities is stiffer than that of the MIT bag model. At high densities it tends to the ultrarelativistic behavior expected because of the asymptotic freedom of quarks. The density of zero pressure is near the one predicted by the bag model and not shifted away as stated before; nevertheless, at these densities the velocity of sound is ≊50% larger in this model than in the bag model. We have integrated the equations of stellar structure for strange stars with the present equation of state. We found that the mass-radius relation is very much the same as in the bag model, although it extends to more massive objects, due to the stiffening of the equation of state at low densities.

In this article we study the surface tension and the curvature energy of three-flavor quark matter in equilibrium under weak interactions within the Nambu–Jona-Lasinio model. We include the effect of color superconductivity and describe finite size effects within the multiple reflection expansion framework. Our calculations result in large values of the surface tension which disfavor the formation of mixed phases at the hadron-quark interphase inside a hybrid star.

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics