Particle clustering and Mott transitions in nuclear matter at finite temperature: (I). Method and general aspects

The thermodynamic state of nuclear matter as regards dependence on density and temperature is considered. Expressions for the association degree are derived describing the ratio of nuclear matter which is clustered to bound states. The problem of two nucleons imbedded in the surrounding nuclear matter is considered with the help of the Bethe-Goldstone equation for thermodynamic Green functions. The two-particle energy shift due to the effective nuclear matter hamiltonian is considered in a Hartree-Fock approximation, and a Mott density is obtained so that for densities of nuclear matter higher than the Mott density bound states cannot exist. With a simplified effective two-nucleon interaction the association degree is calculated as a function of the nucleon density and the temperature.     

Incompressibility and single-particle potential for asymmetric nuclear matter with Skyrme potential

The incompressibility and the single-particle potential of asymmetric nuclear matter have been investigated in the framework of the Skyrme interaction. These parameters have been studied as functions of the nuclear density, the neutron excess parameter, and the temperature. The ratio of the isothermal incompressibility of hot nuclear matter to the incompressibility of cold nuclear matter for different values of neutron excess as a function of temperature is calculated. It is observed that this ratio decreases with temperature increasing apart from pure neutron matter when the growth of temperature leads to the growth of incompressibility. The symmetry incompressibility has been calculated as a function of density for different values of temperature. The text was submitted by the authors in English.     

Pion condensation at finite temperature: (I). Mean field theory

The pion-condensed state of neutron-rich matter at finite temperature is calculated within the framework of a simple σ-model, treating the pion field as a mean field. At high densities the matter is condensed with a spatially non-uniform condensate. However, we find the unexpected result that as the density is lowered, at any finite temperature, pure neutron matter always makes a transition to a state with a spatially uniform condensate. Pure neutron matter, within mean field theory, is condensed at all non-zero temperatures and densities. Matter with a small proton fraction at zero temperature has a qualitatively similar phase diagram, except that it is normal when both the temperature and density are sufficiently low.     

Transition to hot quark matter in relativistic heavy-ion collision

The nuclear matter-quark matter phase transition density is calculated as a function of temperature. The result suggests a transition to quark matter in heavy-ion collision at laboratory kinetic energies of a few GeV per nucleon. The transition may be inferred by observing a limiting temperature for the hadrons produced by the collision.     

Sound of Speed in Nuclear Matter with Skyrme Forces

An analytical expression for sound of speed in asymmetric nuclear matter is acquired, based on the thermal Fermi-gas model and Skyrme-type nucleon-nucleon interactions. A low temperature high density approximation is adopted to the Fermi-Dirac integrals. The dependence of sound of apeed on the temperature and density bf nuclear matter under consideration ie investigated. For all the cases concerned, the so-called superluminosity is observed, the position of which is found to depend on the force parameters used and the asymmetric parameter of the nuclear matter. A possible way to avoid this causal-constraint violation is suggested.     

Properties of hadron and quark matter studied with molecular dynamics

We study the hadron-quark phase transition in a molecular dynamics (MD) of quark degrees of freedom. The hadron state at low density and temperature, and the deconfined quark state at high density and temperature are observed in our model. We investigate the equations of state and draw the phase diagram at wide baryon density and temperature range. We also discuss the transport property, e.g. viscosity, of $q\bar q$ matter. It is found that the ratio of the shear viscosity to the entropy density is less than one for quark matter.     

On the Liguid-Gas Phase Transition and the Instability of Hot Nuclei

Based on a simple semi-empirical energy density, the free energy density for a hot nucleon system is derived, from which the equations of state P(T, p) and chemical potentials μ_q(T, p) for both finite nucleus and infinite nuclear matter are acquired. The liquid-gas phase transition and the instability of hot nuclei are analysed with these ingredients within the framework of thermodynamic's. Both critical temperature T_c for infinite nuclear matter and limiting temperature T_lim, for finite nuclei are predicted and compared with previous calculations.     

Constraints for critical temperature of the phase transition into the quark-gluon plasma

Low temperature of the phase transition into the quark-gluon plasma correspond to low values of the bag model constant and to absolutely stable strange quark matter. Some of the observed pulsars are identified quite reliably as neutron stars. If strange matter is stable, the central density of these pulsars is to be smaller that critical density of the phase transition into the nonstrange quark matter. The nonstrange quark matter being formed turns to more stable strange matter on a weak interaction timescale converting neutron stars into strange stars. The requirement of stability of old and newly born neutron stars is used to constrain the bag model constant and the critical temperature of the phase transition into the quark-gluon plasma at zero chemical potential.     

致密物质性质和适用于超新星及中子星研究的状态方程(英文)

采用相对论平均场方法研究了致密物质的性质, 构造了包括较宽温度、 同位旋不对称度和密度范围的适用于超新星模拟研究的状态方程, 均匀物质由相对论平均场理论描述, 非均匀物质由托马斯 费米近似给出。讨论了包含超子自由度的中子星物质的状态方程。 计算结果表明, 包含超子可以有效地软化高密度区的状态方程, Λ超子的超流态有可能存在于大质量中子星内部。The properties of dense matter are studied within the relativistic mean field theory. The equation of state (EOS) of dense matter are constructed covering a wide range of temperature, proton fraction, and density for the use of supernova simulations. The relativistic mean field theory is employed to describe the uniform matter, while the Thomas Fermi approximation is adopted to describe the non uniform matter. The EOS of neutron star matter is discussed with the inclusion of hyperons. It is found that the EOS at high density can be significantly softened by the inclusion of hyperons. The 1S₀ superfluidity of Λ hyperons may exist in massive neutron stars.     

Pseudoscalar neutral mesons in hot and dense matter

The behavior of neutral pseudoscalar mesons π⁰,η and η′ in hot and dense matter is investigated, in the framework of the three flavor Nambu–Jona-Lasinio model. Three different scenarios are considered: zero density and finite temperature, zero temperature and finite density in a flavor asymmetric medium with and without strange valence quarks, and finite temperature and density. The behavior of mesons is analyzed in connection with possible signatures of restoration of symmetries. In the high density region and at zero temperature it is found that the mass of the η′ increases, the deviation from the mass of the η being more pronounced in matter without strange valence quarks.     

铁热稠密物质状态方程的相对论Hartree-Fock-Slater计算

 本文在球元胞、中心力场、相对论Fermi统计近似下，用平均原子模型计算铁热稠密物质在任意温度和密度下的单电子能级和状态方程。这种算法以Zink的解析拟合势作为初始势，求解满足Wigner-Seitz边界条件的Dirac-Slater径向波函数方程。通过简并度是密度的连续函数，考虑了大密度的压致电离效应。这样从另一个角度考虑了电子的能带结构。     

THE PROPERTIES OF NUCLEAR MATTER AT LOW TEMPERATURE IN A POSSIBLE QUARK MECHANISM

In this paper,the nucleon is described by the MIT bag model,and the internal quark motion in the nucleon is modified by the scalar and vector meson fields.The Fermi motion of nucleon in nuclear matter is considered.The changes for intrinsic properties of nucleon in nuclear matter at different temperature are calculated as a function of the density.The binding energy per nucleon for different temperature is given.     

Particle hole state densities

The influence of correlations on the critical temperature and density for the onset of superfluidity in nuclear matter is investigated within the scheme of Nozières and Schmitt-Rink [1]. For symmetric nuclear matter a smooth transition from Bose-Einstein condensation (BEC) of deuteronlike bound states at low densities and low temperatures to Bardeen-Cooper-Schrieffer (BCS) pairing at higher densities is described. Compared with the mean field approach a lowering of the critical temperature is obtained for symmetric nuclear matter as well as for pure neutron matter. The Mott transition in symmetric nuclear matter is discussed. Regions in the temperature-density plane are identified where correlated pairs give the main contribution to the composition of the system, so that approximations beyond the quasi-particle picture are requested.     

热核物质中单核子势的重排项贡献和三体核力效应

在包含三体核力的有限温度Brueckner-Hartree-Fock理论方法基础上, 利用质量算子的空穴线展开, 研究了热核物质中基态关联所导致的对单核子势的重排修正项的密度和温度依赖性, 并讨论了三体核力对重排项的影响. 结果表明：单核子势的重排项贡献具有较强的密度和温度相关性, 重排项贡献随密度增加而增强并随温度升高而减弱. 在计算中引入三体核力会在一定程度上抑制基态空穴关联 效应, 从而导致单核子势的重排项贡献减小, 而且三体核力对重排项贡献的影响随密度增大而增强.     

Density effects of heavy-ion stopping power in high temperature matter

Abstract

The stopping power and range for Xe ions in high temperature matter (partially ionized plasmas) have been calculated using the dielectric response function method. Calculations have been made for a target matter Al (Z = 13) over a wide range of temperatures and densities considering a finite temperature model. The stopping powers obtained have smaller values in comparison with those of a zero temperature model. The stopping power strongly depends on the density and temperature of the target material, and the projectile ion energy.     

在热密物质中的J/Ψ分解

用误差函数形式的禁闭位加上库仑形式的单胶子位研究了（ｃｃ）和（ｂｂ）质量谱，并用热场动力学近似研究了在有限温度和有限密度下的Ｄｅｂｙｅ屏蔽质量，得到在热密物质中Ｊ／Ψ分解的临界温度和临界能量密度．     

Nuclear matter at high density: Phase transitions,multiquark states,and supernova outbursts

Phase transition from hadronic matter to quark-gluon matter is discussed for various regimes of temperature and baryon number density. For small and medium densities, the phase transition is accurately described in the framework of the Field Correlation Method, whereas at high density predictions are less certain and leave room for the phenomenological models. We study formation of multiquark states (MQS) at zero temperature and high density. Relevant MQS components of the nuclear matter can be described using a previously developed formalism of the quark compound bags (QCB). Partialwave analysis of nucleon-nucleon scattering indicates the existence of 6QS which manifest themselves as poles of P matrix. In the framework of the QCB model, we formulate a self-consistent system of coupled equations for the nucleon and 6QS propagators in nuclear matter and the G matrix. The approach provides a link between high-density nuclear matter with the MQS components and the cumulative effect observed in reactions on the nuclei, which requires the admixture of MQS in the wave functions of nuclei kinematically. 6QS determines the natural scale of the density for a possible phase transition into theMQS phase of nuclear matter. Such a phase transition can lead to dynamic instability of newly born protoneutron stars and dramatically affect the dynamics of supernovae. Numerical simulations show that the phase transition may be a good remedy for the triggering supernova explosions in the spherically symmetric supernovamodels. A specific signature of the phase transition is an additional neutrino peak in the neutrino light curve. For a Galactic core-collapse supernova, such a peak could be resolved by the present neutrino detectors. The possibility of extracting the parameters of the phase of transition from observation of the neutrino signal is discussed also.     

J/ψ Dissociation in Hot and Dense Matter

The energy spectra of heavy quark bound states are analyzed using the error-function-type potential and the one-gluon-exchange Coulomb-type force. The Debye screening mass at finite temperature and density is studied in the thermofield dynamics approach. The critical temperature and cridcal energy density for J/ψ dissociation in hot and dense matter are obtained.     

Non-equilibrium nuclear abundances in superdense matter

1. The equation of state and nuclear composition are calculated for cold matter below neutron-drip density (～4×10¹¹ g/cm³) using recent nuclear data. 2. Nuclear transmutations of hot and dense matter taking care of the freezing of nuclear reactions are discussed for three types of temperature and density changes.