3,756 research outputs found
Color superconductivity and the strange quark
At ultra-high density, matter is expected to form a degenerate Fermi gas of
quarks in which there is a condensate of Cooper pairs of quarks near the Fermi
surface: color superconductivity. In these proceedings I review some of the
underlying physics, and discuss outstanding questions about the phase structure
of ultra-dense quark matter.Comment: 11 pages, proceedings of QCD@Work 2005 and Johns Hopkins Workshop
200
Quark matter in neutron stars
According to quantum chromodynamics, matter at ultra-high density and low
temperature is a quark liquid, with a condensate of Cooper pairs of quarks near
the Fermi surface ("color superconductivity"). This paper reviews the physics
of color superconductivity, and discusses some of the proposed signatures by
which we might detect quark matter in neutron stars.Comment: 8 pages, 3 figures; To appear in the conference proceedings for Quark
Matter 2009, March 30 - April 4, Knoxville, Tennessee. v2: typo corrected,
line numbers remove
Viscous damping of r-modes: Large amplitude saturation
We analyze the viscous damping of r-mode oscillations of compact stars,
taking into account non-linear viscous effects in the large-amplitude regime.
The qualitatively different cases of hadronic stars, strange quark stars, and
hybrid stars are studied. We calculate the viscous damping times of r-modes,
obtaining numerical results and also general approximate analytic expressions
that explicitly exhibit the dependence on the parameters that are relevant for
a future spindown evolution calculation. The strongly enhanced damping of large
amplitude oscillations leads to damping times that are considerably lower than
those obtained when the amplitude dependence of the viscosity is neglected.
Consequently, large-amplitude viscous damping competes with the gravitational
instability at all physical frequencies and could stop the r-mode growth in
case this is not done before by non-linear hydrodynamic mechanisms.Comment: 18 pages, 17 figures, changed convention for the r-mode amplitude,
version to be published in PR
What the Timing of Millisecond Pulsars Can Teach us about Their Interior
The cores of compact stars reach the highest densities in nature and
therefore could consist of novel phases of matter. We demonstrate via a
detailed analysis of pulsar evolution that precise pulsar timing data can
constrain the star's composition, through unstable global oscillations
(r-modes) whose damping is determined by microscopic properties of the
interior. If not efficiently damped, these modes emit gravitational waves that
quickly spin down a millisecond pulsar. As a first application of this general
method, we find that ungapped interacting quark matter is consistent with both
the observed radio and x-ray data, whereas for ordinary nuclear matter some
additional enhanced damping mechanism is required.Comment: 6 pages, 5 figures, version to be published in PR
Ginzburg-Landau approach to the three flavor LOFF phase of QCD
We explore, using a Ginzburg-Landau expansion of the free energy, the
Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase of QCD with three flavors, using
the NJL four-fermion coupling to mimic gluon interactions. We find that, below
the point where the QCD homogeneous superconductive phases should give way to
the normal phase, Cooper condensation of the pairs u-s and d-u is possible, but
in the form of the inhomogeneous LOFF pairing.Comment: 8 pages, 4 figures. Eq. (20) corrected. As a consequence figures have
been modified to show only the solution with parallel total momenta of the
us, ud pairs, as the other configurations are suppressed. Main conclusions of
the paper are unchange
Resummed one-loop gluonic contributions to the color superconducting color charge density vanish
It is shown that gluonic corrections to the tadpole diagrams vanish in the
2SC and CFL phases at the order where one might have expected NLO corrections.
This implies that the gluonic part of the color charge density is negligible at
the order of our computation. This statement remains true after inclusion of
the gluon vertex correction and contributions from Nambu-Goldstone bosons.Comment: 9 pages, 3 figures, REVTeX4; title modified, comments about gauge
independence added, accepted for publication in Phys. Rev.
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