非对称核物质中质子和中子的1S0态超流性

利用Brueckner-Hartree-Fock和BCS理论方法，计算了非对称核物质中处于¹S₀态的质子和中子的对关联能隙，着重研究和讨论了能隙的同位旋依赖性和三体核力的影响.结果表明：随核物质的同位旋非对称度增大，中子¹S₀态超流相存在的密度范围逐渐缩小而且对关联能隙峰值稍有升高；质子¹S₀态超流相存在的密度范围迅速扩大而且对关联能隙峰值显著降低.三体核力对非对称核物质中¹S₀态中子超流性及其同位旋依赖性的影响相对较小，但对¹S₀态质子超流性具有重要影响，而且其效应随核子数密度增大而迅速增强.三体核力的主要作用是强烈地抑制了具有高非对称度的核物质中高密度区域的¹S₀态质子超流性，导致质子超流相存在的密度范围显著缩小. 关键词： 同位旋非对称核物质 质子和中子超流性 三体核力 BCS理论     

Neutral color-spin-locking phase in neutron stars

We present results for the spin-1 color-spin-locking (CSL) phase using a NJL-type model in two-flavor quark matter for compact stars applications. The CSL condensate is flavor symmetric and therefore charge and color neutrality can easily be satisfied. We find small energy gaps ≃ 1MeV, which make the CSL matter composition and the EoS not very different from the normal quark matter phase. We keep finite quark masses in our calculations and obtain no gapless modes that could have strong consequences in the late cooling of neutron stars. Finally, we show that the region of the phase diagram relevant for neutron star cores, when asymmetric flavor pairing is suppressed, could be covered by the CSL phase.     

Rapid cooling of the neutron star in Cassiopeia A triggered by neutron superfluidity in dense matter

We propose that the observed cooling of the neutron star in Cassiopeia A is due to enhanced neutrino emission from the recent onset of the breaking and formation of neutron Cooper pairs in the (3)P(2) channel. We find that the critical temperature for this superfluid transition is ?0.5×10(9) K. The observed rapidity of the cooling implies that protons were already in a superconducting state with a larger critical temperature. This is the first direct evidence that superfluidity and superconductivity occur at supranuclear densities within neutron stars. Our prediction that this cooling will continue for several decades at the present rate can be tested by continuous monitoring of this neutron star.     

Nuclear superfluidity and cooling time of neutron stars

We discuss how the nuclear superfluidity affects the thermalisation time of the inner crust of neutron star in the case of a rapid cooling process. The thermal response of the inner crust matter is calculated supposing two pairing scenarios: one corresponding to the BCS approximation and the other to many-body techniques including polarisation effects. It is shown that these two pairing scenarios, which reflect the present uncertainty in the pairing properties of infinite neutron matter, give very different values for the thermalisation time of the crust.     

QCD at finite density and color superconductivity

The paper contains a brief review of recent applications of many-body theory to quark matter. We discuss the progress in theory of dense quark matter during the last two years, especially color superconductivity. We emphasize that there are two basic dynamical reasons for it: short-range forces induced by instantons and long-range ones mediated by exchanges of magnetic gluons. For quark matter which is supposed to be found in neutron stars, both lead to superconducting gaps on the order of 100 MeV. The most surprising facts are the rather impressive richness of different phases and their robustness in respect to variation of the fundamental interaction.     

Neutron star matter superfluidity and superconductivity

The possibility of superfluidity or superconductivity in neutron or proton subsystems in the nuclear-matter region in neutron stars is investigated. The energy gap and corresponding critical temperature and critical magnetic field is calculated or estimated as function of density or Fermi momentum. In the calculations are used reaction matrix elements calculated earlier by means of Brueckner theory by the author. The final results indicate that neutron superfluidity, corresponding specifically toS-state pairing, may exist in a low-density shell in the nuclear-matter region of a neutron star. There is probably anisotropic neutron superfluidity, corresponding to the³ P ₂ or the singletD state, for higher densities. Superfluidity or superconductivity, corresponding toS-state pairing for the proton subsystem, is quite likely in most of the nuclear-matter region. The expected temperatures and magnetic fields in neutron stars seem to be well below the estimated critical temperatures or critical magnetic fields corresponding to the calculated values of the energy gap. However, similar methods have earlier predicted a much too high critical temperature for liquid³He.     

Thermal evolution and light curves of young bare strange stars

We study numerically the cooling of a young bare strange star and show that its thermal luminosity, mostly due to e(+)e(-) pair production from the quark surface, may be much higher than the Eddington limit. The mean energy of photons far from the strange star is approximately 10(2) keV or even more. This differs both qualitatively and quantitatively from the thermal emission from neutron stars and provides a definite observational signature for bare strange stars. It is shown that the energy gap of superconducting quark matter may be estimated from the light curves if it is in the range from approximately 0.5 MeV to a few MeV.     

Neutrino emissivities in 2SC color-superconducting quark matter

The phase structure and equation of state for two-flavor quark matter under compact star constraints is studied within a nonlocal chiral quark model. Chiral symmetry breaking leads to rather large, density dependent quark masses at the phase transition to quark matter. The influence of diquark pairing gaps and quark masses on density dependent emissivities for the direct URCA is discussed. Since m _u > m _d , the direct URCA process due to quark masses cannot occur. We present cooling curves for model quark stars and discuss their relation to observational data. The text was submitted by the author in English.     

Microscopic theory of strong superfluidity

Various forms of superfluidity in nuclei and nuclear and neutron matter are characterized by the relevance of strong nucleon-nucleon correlations, as well as by gap values, which can be a substantial fraction of the Fermi energy. We present a microscopic many-body theory of nuclear superfluidity. The influence of various physical effects is analyzed within the Green's function formalism and the Bethe-Brueckner-Goldstone expansion. In particular, dispersive effects are discussed in detail. We point out open problems that must be solved before a full understanding of nuclear superfluidity can be achieved.     

3PF2 neutron superfluidity in neutron stars and three-body force effect

We investigate the ^3PF2 neutron superfluidity in H-stable neutron star matter and neutron stars by using the BCS theory and the Brueckner-Hartree-Fock approach. We adopt the Argonne V18 potential supplemented with a microscopic three-body force as the realistic nucleon-nucleon interaction. We have concentrated on studying the threebody force effect on the ^3PF2 neutron pairing gap. It is found that the three-body force effect is to enhance remarkably the ^3PF2 neutron superfluidity in neutron star matter and neutron stars.     

Superfluidity and superconductivity in the universe

The paper aims to elucidate the current status of the problem concerning the existence and observation of superfluid and superconducting states in the universe, that is, under cosmic conditions. Following an introduction, the paper discusses Bose-Einstein condensation, superfluidity, and superconductivity; possibilities for the occurrence of superfluidity and superconductivity under cosmic conditions; superconductivity of dense, degenerate electron plasma (large planets, white dwarfs); superfluidity and superconductivity in neutron stars; and finally superfluidity in a cosmological neutrino “sea.”     

中子物质中超流性的自能色散效应

利用扩展的 Brueckner- Hartree- Fock理论与推广的 BCS方法研究了自能的色散效应和基态关联对中子物质中超流性和能隙的影响 .研究结果表明 ,自能的色散效应使中子物质中能隙减小;考虑基态关联后 ,超流性将进一步减弱. The effects of the dispersion and ground state correlation of the single particle self-energy on neutron matter superfluidity have been investigated in the framework of the Extended Brueckner-Hartree-Fock and the generalized BCS approaches. A sizable reduction of the energy gap is found due to the energy dependence of the self-energy. And the inclusion of the ground state correlations in the self-energy suppresses further the neutron matter superfluidity.     

Superfluidity in neutron stars

Arguments are presented to show that the BCS theory of superfluidity in its original form may not be applicable to neutron star matter over a wide range of density.     

Nonlocality effects on spin-one pairing patterns in two-flavor color superconducting quark matter and compact star applications

We study the influence of nonlocality in the interaction on two spin-one pairing patterns of two-flavor quark matter: the anisotropic blue-color pairing besides the usual two-color superconducting matter (2SCb), in which red and green colors are paired, and the color-spin locking phase (CSL). The effect of nonlocality on the gaps is rather large and the pairings exhibit a strong dependence on the form factor of the interaction, especially in the low-density region. The application of these small spin-one condensates for compact stars is analyzed: the early onset of quark matter in the nonlocal models may help to stabilize hybrid star configurations. While the anisotropic blue-quark pairing does not survive a big asymmetry in flavor space as imposed by the charge neutrality condition, the CSL phase as a flavor independent pairing can be realized as neutral matter in compact star cores. However, smooth form factors and the mismatch between the flavor chemical potential in neutral matter make the effective gaps of the order of magnitude ≃10 keV, and a more systematic analysis is needed to decide whether such small gaps could be consistent with the cooling phenomenology. The text was submitted by the authors in English.     

Quark stars: features and findings

Under extreme conditions of temperature and/or density, quarks and gluons are expected to undergo a deconfinement phase transition. While this is an ephemeral phenomenon at the ultra-relativistic heavy-ion collider (BNL-RHIC), quark matter may exist naturally in the dense interior of neutron stars. Here, we present an appraisal of the possible phase structure of dense quark matter inside neutron stars, and the likelihood of its existence given the current status of neutron star observations. We conclude that quark matter inside neutron stars cannot be dismissed as a possibility, although recent observational evidence rules out most soft equations of state. PACS 97.60.Jd; 26.60.+c     

中子物质中的3PF2态超流性和微观三体核力效应

利用Brueckner-Hartree-Fock(BHF)和BCS理论方法，计算了纯中子物质中处于³PF₂态的中子对关联能隙，特别是研究并讨论了微观三体核力对³PF₂态中子超流性强弱的影响. 结果表明：三体核力显著地增强了中子物质中³PF₂态中子超流性；当采用BHF单粒子能谱时，三体核力导致相应的对关联能隙峰值由0.22MeV增大到0.50MeV. 关键词： 中子物质 3PF₂超流性')" href="#">³PF₂超流性 三体核力 BCS理论     

Superfluidity in neutron matter

The question of superfluidity in neutron matter is investigated in the framework of BCS-Bogoljubov-Theory. Solving the gap-equation for a semirealistic hard-core and a soft-core potential, a rapidly converging numerical method is developed. The results are applied to neutron star models.     

Quark deconfinement in neutron star cores

Whether or not the deconfined quark phase exists in neutron star cores is an open question. We use two realistic effective quark models, the three-flavor Nambu-Jona-Lasinio model and the modified quark-meson coupling model, to describe the neutron star matter. We show that the modified quark-meson coupling model, which is fixed by reproducing the saturation properties of nuclear matter, can be consistent with the experimental constraints from nuclear collisions. After constructing possible hybrid equations of state (EOSes) with an unpaired or color superconducting quark phase with the assumption of the sharp hadron-quark phase transition, we discuss the observational constraints from neutron stars on the EOSes. It is found that the neutron star with pure quark matter core is unstable and the hadronic phase with hyperons is denied, while hybrid EOSes with a two-flavor color superconducting phase or unpaired quark matter phase are both allowed by the tight and most reliable constraints from two stars Ter 5 I and EXO 0748-676. And the hybrid EOS with an unpaired quark matter phase is allowed even compared with the tightest constraint from the most massive pulsar star PSR J0751+1807.     

Phase transition to color-flavor-locked matter and condensation of Goldstone bosons in neutron star matter

Deconfinement phase transition and condensation of Goldstone bosons in neutron star matter are investigated in a chiral hadronic model (also referred as to the FST model) for the hadronic phase (HP) and in the color-flavor-locked (CFL) quark model for the deconfined quark phase. It is shown that the hadronic-CFL mixed phase (MP) exists in the center of neutron stars with a small bag constant, while the CFL quark matter cannot appear in neutron stars when a large bag constant is taken. Color superconductivity softens the equation of state (EOS) and decreases the maximum mass of neutron stars compared with the unpaired quark matter. The K⁰ condensation in the CFL phase has no remarkable contribution to the EOS and properties of neutron star matter. The EOS and the properties of neutron star matter are sensitive to the bag constant B, the strange quark mass m_s and the color superconducting gap Δ. Increasing B and m_s or decreasing Δ can stiffen the EOS which results in the larger maximum masses of neutron stars.     

Quarksonic matter at high isospin density

Analogous to the quarkyonic matter at high baryon density in which the quark Fermi seas and the baryonic excitations coexist,it is argued that a "quarksonic matter" phase appears at high isospin density where the quark(antiquark) Fermi seas and the mesonic excitations coexist.We explore this phase in detail in both large Nc and asymptotically free limits.In the large Nc limit,we sketch a phase diagram for the quarksonic matter.In the asymptotically free limit,we study the pion superfluidity and thermodynamics of the quarksonic matter by using both perturbative calculations and an effective model.