Revisting the boiling of quark nuggets at nonzero chemical potential

Abstract

The boiling of possible quark nuggets during the quark-hadron phase transition of the Universe at nonzero chemical potential is revisited within the microscopic Brueckner-Hartree-Fock approach employed for the hadron phase, using two kinds of baryon interactions as fundamental inputs. To describe the deconfined phase of quark matter, we use a recently developed quark mass density-dependent model with a fully self-consistent thermodynamic treatment of confinement. We study the baryon number limit $A_{\mathrm{boil}}$ (above which boiling may be important) with three typical values for the confinement parameter $D$. It is firstly found that the baryon interaction with a softer equation of state for the hadron phase would only lead to a small increase of $A_{\mathrm{boil}}$. However, results depend sensitively on the confinement parameter in the quark model. Specifically, boiling might be important during the Universe cooling for a limited parameter range around $D^{1/2}=170$ MeV, a value satisfying recent lattice QCD calculations of the vacuum chiral condensate, while for other choices of this parameter, boiling might not happen and cosmological quark nuggets of $10^2<A<10^{50}$ could survive.

Comments: 6 figures, 18 pages, Astropart. Phys. (2014) accepted