11 research outputs found
The phase diagram of neutral quark matter: Self-consistent treatment of quark masses
We study the phase diagram of dense, locally neutral three-flavor quark
matter within the framework of the Nambu--Jona-Lasinio model. In the analysis,
dynamically generated quark masses are taken into account self-consistently.
The phase diagram in the plane of temperature and quark chemical potential is
presented. The results for two qualitatively different regimes, intermediate
and strong diquark coupling strength, are presented. It is shown that the role
of gapless phases diminishes with increasing diquark coupling strength.Comment: 10 pages, 7 figures. Two new figures added as in the published
versio
The outer crust of non-accreting cold neutron stars
The properties of the outer crust of non-accreting cold neutron stars are
studied by using modern nuclear data and theoretical mass tables updating in
particular the classic work of Baym, Pethick and Sutherland. Experimental data
from the atomic mass table from Audi, Wapstra, and Thibault of 2003 is used and
a thorough comparison of many modern theoretical nuclear models, relativistic
and non-relativistic ones, is performed for the first time. In addition, the
influences of pairing and deformation are investigated. State-of-the-art
theoretical nuclear mass tables are compared in order to check their
differences concerning the neutron dripline, magic neutron numbers, the
equation of state, and the sequence of neutron-rich nuclei up to the dripline
in the outer crust of non-accreting cold neutron stars.Comment: 20 pages, 10 figures, accepted for publication in Phys. Rev.
Phase diagram of dense neutral three-flavor quark matter
We study the phase diagram of dense, locally neutral three-flavor quark
matter as a function of the strange quark mass, the quark chemical potential,
and the temperature, employing a general nine-parameter ansatz for the gap
matrix. At zero temperature and small values of the strange quark mass, the
ground state of matter corresponds to the color-flavor-locked (CFL) phase. At
some critical value of the strange quark mass, this is replaced by the recently
proposed gapless CFL (gCFL) phase. We also find several other phases, for
instance, a metallic CFL (mCFL) phase, a so-called uSC phase where all colors
of up quarks are paired, as well as the standard two-flavor
color-superconducting (2SC) phase and the gapless 2SC (g2SC) phase.Comment: 14 pages, 11 figures, references added; the version accepted for
publication in Nucl. Phys.
Gapless phases of color-superconducting matter
We discuss gapless color superconductivity for neutral quark matter in beta
equilibrium at zero as well as at nonzero temperature. Basic properties of
gapless superconductors are reviewed. The current progress and the remaining
problems in the understanding of the phase diagram of strange quark matter are
discussed.Comment: 8 pages, 2 figures. Plenary talk at Strangeness in Quark Matter 2004
(SQM2004), Cape Town, South Africa, 15-20 September 2004. Minor correction
Effect of color superconductivity on the mass and radius of a quark star
We compare quark stars made of color-superconducting quark matter to
normal-conducting quark stars. We focus on the most simple
color-superconducting system, a two-flavor color superconductor, and employ the
Nambu-Jona-Lasinio (NJL) model to compute the gap parameter and the equation of
state. By varying the strength of the four-fermion coupling of the NJL model,
we study the mass and the radius of the quark star as a function of the value
of the gap parameter. If the coupling constant exceeds a critical value, the
gap parameter does not vanish even at zero density. For coupling constants
below this critical value, mass and radius of a color-superconducting quark
star change at most by ca. 20% compared to a star consisting of
normal-conducting quark matter. For coupling constants above the critical value
mass and radius may change by factors of two or more.Comment: 16 pages, 9 figure