Supercurrents in color-superconducting quark matter

We review the basic properties of the currCFL-K⁰ phase in dense quark matter. At asymptotically large densities, three-flavor quark matter is in the color-flavor locked (CFL) state. The currCFL-K⁰ state is a way to respond to “stress” on the quark Cooper pairing, imposed at more moderate densities by the strange quark mass and the conditions of electric and color neutrality. We show how a kaon supercurrent is incorporated in a purely fermionic formalism, and show that the net current vanishes due to cancellation of fermion and charge-conjugate fermion contributions.     

Anisotropic admixture in color-superconducting quark matter

The analysis of color-superconducting two-flavor deconfined quark matter at moderate densities is extended to include a particular spin-1 Cooper pairing of those quarks which do not participate in the standard spin-0 diquark condensate. (i) The relativistic spin-1 gap delta(') implies spontaneous breakdown of rotation invariance manifested in the form of the quasifermion dispersion law. (ii) The critical temperature of the anisotropic component is approximately given by the relation T(')(c) approximately delta(')(T=0)/3. (iii) For massless fermions the gas of anisotropic Bogolyubov-Valatin quasiquarks becomes effectively gapless and two dimensional. Consequently, its specific heat depends quadratically on temperature. (iv) All collective Nambu-Goldstone excitations of the anisotropic phase have a linear dispersion law and the whole system remains a superfluid. (v) The system exhibits an electromagnetic Meissner effect.     

Neutrino emissivity of quark matter at finite temperatures

We evaluate the emissivity rates for d-decay and s-decay by exactly solving the angular integrals involved and without assuming the degeneracy of electrons. We have also studied the effects of QCD coupling constant as well as the s-quark mass on the emissivity rates. We find that these parameters are important in determining the threshold and extinction densities for d- and s-decays.     

Effect of gauge-field fluctuations on the phase transition between normal and color-superconducting quark matter

Type-I color superconductors display a first-order phase transition due to thermal gauge-field fluctuations. We numerically evaluated the critical temperature of the first-order phase transition and the corresponding discontinuity of the diquark condensate at the critical point.     

Neutrino emissivity from strange matter having density dependent quark masses

We have analyzed the equilibrium composition of quark matter consisting of approximately equal number of up, down and strange quarks, based upon the confinement mechanism of Fowler et al. (1981) and Plümmer et al. (1984) in which the quark masses are considered density dependent. Using this model, we calculate the neutrino emissivity rate and the neutrino mean free path in quark matter and compare the results with Iwamoto (1982). We find that the emissivity rate is a slowly increasing function of the density, while the values of mean free path are slightly on the higher side than those of Iwamoto.     

Superconductivity in quark matter

Superconductivity due to the pairing of relativistic quarks in ultra-dense matter is discussed. Ginzburg-Landau equations are derived, and the possibility of an Abrikosov vortex phase is considered.     

Superconducting quark matter

In asymptotically dense quark matter, colored glue forces cause an unusual variant of superconductivity. Instead of pairing, the quarks clump in groups of six. We investigate the gap equation in the weak coupling limit, and find the leading behavior of the energy gap and the critical temperature as functions of the renormalized coupling constant.     

Neutrino in matter and external fields

A technique for describing various processes proceeding in matter and involving neutrinos and electrons is discussed. This technique is based on “the method of exact solutions,” which implies the use of solutions to proper Dirac equations for particle wave functions in matter. Exact solutions for the neutrino and the electron in the cases of uniform nonmoving and rotating matter are discussed. On studying relativistic neutrino motion and associated neutrino-energy quantization in rotating matter, a semiclassical interpretation of particle finite motion is developed. In the general case of neutrino and electron motion in matter with varying parameters, the corresponding effective force acting on the particles is determined. The possibility of electromagnetic-wave radiation by an electron that moves in a dense neutrino flux of varying density and which is accelerated by this kind of force is predicted.     

Neutrino interactions in dense stellar matter

Weak-interaction rates play an important role in the birth of neutron stars in core collapse supernova and their subsequent thermal evolution. In this paper, I highlight the role of strong interactions and phase transitions in calculations of neutrino scattering and emission rates in dense stellar matter.Received: 1 November 2002, Published online: 15 July 2003PACS: 13.15.+g Neutrino interactions - 13.20.-v Leptonic and semileptonic decays of mesons - 26.50.+x Nuclear physics aspects of novae, supernovae, and other explosive environments - 26.60.+c Nuclear matter aspects of neutron starsPresent address: Los Alamos National Laboratory, P.O. Box 1663, MS B283, Los Alamos, NM 87545, USA     

Neutrino opacity in cold neutron matter

The weak dynamic form factors of cold neutron matter have been calculated within correlated basis function (CBF) theory using a realistic Hamiltonian. The results show that the effect of nucleon-nucleon correlations on the density and spin-density responses are different. The role of long-range correlations has been investigated comparing the CBF responses to those resulting from Landau theory of Fermi liquids. The neutrino mean free path has been obtained combining the two approaches. The text was submitted by the authors in English.     

Quark-clustering in cold quark matter

Quarks are proposed to be grouped together to make quark-clusters due to the strong interaction in cold quark matter at a few nuclear densities,because a weakly coupling treatment of the interaction between quarks there would be inadequate.Cold quark matter is then conjectured to be in solid state （i.e.,forming a crystal structure） if the inter-cluster potential is deep enough to localize clusters in lattice.Such a solid state of cold quark matter would be very necessary for us to understand different manifestations of pulsar-like compact stars,and could not be ruled by first principles.     

Superfluidity in ultra-relativistic quark matter

Possible forms of superfluid order parameter are discussed for quark matter at densities where the Fermi energy is much greater than the mass of the quarks. Ginzburg-Landau equations for the order parameter are derived and solved.     

Color superconductivity in quark matter

Selected problems related to color superconductivity are discussed in a rather elementary way. The text was submitted by the author in English.     

Quark-clustering in cold quark matter

Quarks are proposed to be grouped together to make quark-clusters due to the strong interaction in cold quark matter at a few nuclear densities, because a weakly coupling treatment of the interaction between quarks there would be inadequate. Cold quark matter is then conjectured to be in solid state (i.e., forming a crystal structure) if the inter-cluster potential is deep enough to localize clusters in lattice. Such a solid state of cold quark matter would be very necessary for us to understand different manifestations of pulsar-like compact stars, and could not be ruled by first principles.     

Neutrino radiation from dense matter

This article provides a concise review of the problem of neutrino radiation from dense matter. The subjects addressed include quantum kinetic equations for neutrino transport, collision integrals describing neutrino radiation through charged and neutral current interactions, and radiation rates from pair-correlated baryonic and color superconducting quark matter. The text was submitted by the author in English.     

Gapless color-flavor-locked quark matter

In neutral cold quark matter that is so dense that the strange quark mass Ms is unimportant, all three quark flavors pair in a color-flavor locked (CFL) pattern, and all nine fermionic quasiparticles have a gap Delta (or 2Delta). We argue that, as the density decreases (or Ms increases), there is a quantum phase transition (at M(2s/mu approximately 2Delta) to a new "gapless CFL phase" in which only seven quasiparticles have a gap. There is still an unbroken U(1)(Q) gluon/photon, but, unlike CFL, gapless CFL is a Q conductor with gapless (charged) quasiquarks and a nonzero electron density at zero temperature, so its low energy effective theory and astrophysical properties are qualitatively new. At the transition, the dispersion relations of both gapless quasiparticles are quadratic, but for larger M2s/mu, one becomes conventionally linear while the other remains quadratic, up to tiny corrections.     

Faces of quark matter

Based on an analysis in the framework of a coalescence hadronization model (ALCOR) we conclude that in heavy ion collisions at CERN SPS and RHIC energies a new type of matter, the massive quark-antiquark matter is produced.