Effects of 5 Meson on Thermal Protoneutron Star Matter

In the framework of the relativistic mean field theory, the effects of the 6 meson on protoneutron star matter with hyperons at finite temperature are investigated. In thermal protoneutron star matter, the 6 field potential increases with density first and then decreases. Fixing the density, the increase of the temperature suppresses the 6 field potential. With the inclusion of the 6 meson, the threshold densities for hyperons become lower and the abundance of trapped neutrinos decreases. The most important effect of the 6 meson is to increase the abundance of hyperons in the inner core range of protoneutron stars. With the rise of the temperature, the density range where the 6 meson plays an important role is narrowed and the effects of the 6 meson are suppressed. Moreover, the protoneutron star mass and radius are nearly not affected by the 6 meson.     

Thermal protoneutron stars with hyperons

The properties of thermal protoneutron star matter including hyperons are investigated in the framework of the relativistic mean field theory (RMFT). In protoneuron star matter, with the increase of the temperature, the critical densities of hyperons decrease, the sequence for appearances of hyperons change, the abundances of hyperons as well as neutrinos increase, and the strong interactions between baryons get weaker. Meanwhile, the abundances of isospin multiple states for nucleons, Σ, and ■ become identical, leading to isospin saturated symmetric matter, respectively. Moreover, if a protoneutron star is born with higher temperature, it is less likely to convert to a black hole.     

Thermal protoneutron stars with hyperons

The properties of thermal protoneutron star matter including hyperons are investigated in the framework of the relativistic mean field theory (RMFT). In protoneuron star matter, with the increase of the temperature, the critical densities of hyperons decrease, the sequence for appearances of hyperons change, the abundances of hyperons as well as neutrinos increase, and the strong interactions between baryons get weaker. Meanwhile, the abundances of isospin multiple states for nucleons, Σ, and Ξ become identical, leading to isospin saturated symmetric matter, respectively. Moreover, if a protoneutron star is born with higher temperature, it is less likely to convert to a black hole.     

Effects of the δ meson on the direct Urca processes in neutron stars

In the framework of the relativistic mean field theory, the effects of the δ meson on the direct Urca (DURCA) processes are investigated. In a neutron star, the DURCA processes involving nucleons, Λ and Ξ^- can take place while the process involving the Ξ⁰ can not. With the inclusion of the δ meson, the threshold densities for the DURCA processes become lower. With the δ included, the threshold neutron star mass for the DURCA process among nucleons and electrons becomes smaller while the threshold masses for the processes involving hyperons become larger. When the δ meson is included, the total neutrino emissivity remarkably increases in the density range of 0.32--0.41 fm^-3. The total neutrino luminosity increases with the neutron star mass first and then decreases. The neutrino luminosity gets larger with the inclusion of the δ meson. The cooling of the EXO0748-676 is sensitive to the isovector scalar interaction.     

Vacuum fluctuation effects on hyperonic neutron star matter

The vacuum fluctuation （VF） effects on the properties of the hyperonic neutron star matter are investigated in the framework of the relativistic mean field （RMF） theory. The VF corrections result in the density dependence of in-medium baryon and meson masses. We compare our results obtained by adopting three kinds of meson-hyperon couplings. The introduction of both hyperons and VF corrections softens the equation of state （EoS） for the hyperonic neutron star matter and hence reduces hyperonic neutron star masses. The presence of the δ field enlarges the masses and radii of hyperonic neutron stars. Taking into account the uncertainty of meson-hyperon couplings, the obtained maximum masses of hyperonic neutron stars are in the range of 1.33M⊙-1.55M⊙.     

超子耦合参数对热前中子星物质的影响

在相对论平均场理论框架内,利用Λ超子的结合能和中子星质量的观测数据得到超子标量介子耦合参数χσ的范围是0.33—0.77。在这个范围内, 研究了χσ取不同值时, 包含核子, Λ和Ξ超子的热前中子星（固定单个重子熵s=1）的性质。结果表明, 如果超子耦合参数变大, 前中子星核心温度变高, 中微子丰度变低, 前中子星的亚稳态质量范围变小。如果χσ超过了0.75, 前中子星不可能演变成黑洞。联系SN1987A讨论了这一结果的意义。In the framework of the relativistic mean field theory(RMFT), protoneutron stars with hyperons are studied. To be compatible with neutron star masses, the hyperon scalar coupling χσ should lie in the range of 0.33—0.77. As the hyperon scalar coupling increases, in protoneutron star matter, the core temperature increases whereas the abundance of neutrinos decreases. The metastable mass range of protoneutron stars narrows as the temperature increases. It is found that a protoneutron star cannot subside into a low mass black hole when χσ>0.75. Furthermore, the case of SN1987A is discussed.     

Transition density of the large mass hyperon star

The difference between the transition density of a larger mass hyperon star(for example,the neutron star PSR J1614-2230)and that of a smaller mass hyperon star is investigated in the framework of the relativistic mean field theory.We see that the transition density poH increases with the increase of xw(i.e.the mass of the neutron star).For the nucleons parts,the neutrons make the main contribution to the transition density as the baryon density p=poH.With the increase of the x_ω(i.e.the mass of the neutron star),the relative particle number density of neutrons decreases while that of protons increases.For the parts of hyperons,the A andΣ~-make the main contributions to the transition density as the baryon density p=pOH.The relative particle number density of A decreases while that of E~increases with the increase of the x_ω(i.e.the mass of the neutron star).For the hyperonsΣ~-,Σ~0 and E~-,the total contributions are less than 16 per cent.     

Effects of a Weakly Interacting Light U Boson on Protoneutron Stars Including the Hyperon-Hyperon Interactions

In the framework of the relativistic mean field theory including the hyperon-hyperon(YY) interactions,protoneutron stars with a weakly interacting light U boson are studied. The U-boson leads to the increase of the star maximum mass. The modification to the maximum mass by the U-boson with the strong YY interaction is larger than that with the weak YY interaction. The maximum mass of the protoneutron star is less sensitive to the U-boson than that of the neutron star. The inclusion of the U-boson narrows down the mass window for the hyperonized protoneutron stars. As g~2/μ~2 increases, the species of hyperons, which can appear in a stable protoneutron star decrease. The rotation frequency, the red shift, the momentum of inertia and the total neutrino fraction of PSR J1903-0327 are sensitive to the U-boson and change with g~2/μ~2 in an approximate linear trend. The possible way to constrain the coupling constants of the U-boson is discussed.     

K0 Condensation in Hyperonic Neutron Star Matter

In the framework of the relativistic mean field theory, we investigate K^0 condensation along with K^- condensation in neutron star matter including the baryon octet. The results show that both K^0 and K^- condensations can occur well in the core of the maximum mass stars for relatively shallow optical potentials of K^- in the range of-100 MeV～ -160 MeV. With the increasing optical potential of K^-, the critical densities of K^- decrease and the species of baryons appearing in neutron stars become fewer. The main role of K^0 condensation is to make the abundances of particles become identical leading to isospin saturated symmetric matter including antikaons, nucleons and hyperons. K^- condensation is chiefly responsible for the softening of the corresponding equation of state, which leads to a large reduction in the maximum masses of neutron stars. In the core of massive neutron stars, neutron star matter including rich particle species, such as antikaons, nucleons and hyperons, may exist.     

Survival of charged ρ condensation at high temperature and density

The charged vector ρ mesons in the presence of external magnetic fields at finite temperature T and chemical potential μ have been investigated in the framework of the Nambu-Jona-Lasinio model.We compute the masses of charged ρ mesons numerically as a function of the magnetic field for different values of temperature and chemical potential.The self-energy of the ρ meson contains the quark-loop contribution,i.e.the leading order contribution in 1/N_C expansion.The charged ρ meson mass decreases with the magnetic field and drops to zero at a critical magnetic field eB_c,which indicates that the charged vector meson condensation,i.e.the electromagnetic superconductor can be induced above the critical magnetic field.Surprisingly,it is found that the charged ρ condensation can even survive at high temperature and density.At zero temperature,the critical magnetic field just increases slightly with the chemical potential,which indicates that charged ρ condensation might occur inside compact stars.At zero density,in the temperature range 0.2 — 0.5 GeV,the critical magnetic field for charged ρ condensation is in the range of 0.2 — 0.6 GeV~2,which indicates that a high temperature electromagnetic superconductor might be created at LHC.     

Antikaon Condensation and In-medium Kaon and Antikaon Production in Protoneutron Stars

Antikaon condensation and kaon and antikaon production in protoneutron stars are investigated in a chiral hadronic model （also referred to as the FST model in this paper）. The effects of neutrino trapping on protoneutron stars are analyzed systematically. It is shown that neutrino trapping makes the critical density of K^- condensation delay to higher density and fifo condensation not occur. The equation of state （EOS） of （proto）neutron star matter with neutrino trapping is stiffer than that without neutrino trapping. As a result, the maximum masses of （proto）neutron stars with neutrino trapping are larger than those without neutrino trapping. If hyperons are taken into account, antikaon does not form a condensate in （proto）neutron stars. Meanwhile, the corresponding EOS becomes much softer, and the maximum masses of （proto）neutron stars are smaller than those without hyprons. Finally, our results illustrate that the Q values for K^＋ and K^- production in （proto）neutron stars are not sensitive to neutrino trapping and inclusion of hyperons.     

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.     

In-Medium K^＋ and K^- Production and K^- Condensation in Supernova Matter

In-medium effects and neutrino trapping on K^ and K^- production and K^- condensation in supernova matter are investigated in a chiral hadronic model. Our results show that neutrino trapping shifts the critical density for K^- condensation to higher density, the Q values for K^ and K^- production are not sensitive to neutrino trapping, in-medium effects decrease the Q values for NN→NNK^ K^- and AN→NNK^- and increase those for NN→NAK^ , K^- p→Aπ^0 and K^-n→Aπ^- as the density of supernova matter increases. Moreover, it is shown that neutrino trapping decreases the maximum masses of protoneutron stars compared with the neutrino-free case.     

Supersonic Shock Wave with Landau Quantization in a Relativistic Degenerate Plasma

A three-dimensional(3D)BurgersJ equation adopting perturbative methodology is derived to study the evolution of a shock wave with Landau quantized magnetic field in relativistic quantum plasma.The characteristics of a shock wave in such a plasma under the influence of magnetic quantization,relativistic parameter and degenerate electron density are studied with assistance of steady state solution.The magnetic field has a noteworthy control,especially on the shock wave's amplitude in the lower range of the electron density,whereas the amplitude in the higher range of the electron density reduces remarkably.The rate of increase of shock wave potential is much higher(lower)with a magnetic Held in the lower(higher)range of electron density.With the relativistic factor,the shock wave's amplitude increases significantly and the rate of increase is higher(lower)for lower(higher)electron density.The combined effect of the increase of relativistic factor and the magnetic field on the strength of the shock wave,results in the highest value of the wave potential in the lower range of the degenerate electron density.     

Hyperon coupling dependence of hadron matter properties in relativistic mean field model

The properties of hadronic matter at β equilibrium in a wide range of densities are described by appropriate equations of state in the framework of the relativistic mean field model. Strange meson fields, namely the scalar meson field σ＊（975） and the vector meson field φ（1020）, are included in the present work. We discuss and compare the results of the equation of state, nucleon effective mass, and strangeness fraction obtained by adopting the TM1, TMA, and GL parameter sets for nuclear sector and three different choices for the hypcron couplings. We find that the parameter set TM1 favours the onset of hyperons most, while at high densities the GL parameter set leads to the most hyperon-rich matter. For a certain parameter set （e.g. TM1）, the most hyperon-rich matter is obtained for the hyperon potential model. The influence of the hyperon couplings on the effective mass of nucleon, is much weaker than that on the nucleon parameter set. The nonstrange mesons dominate essentially the global properties of dense hyperon matter. The hyperon potential model predicts the lowest value of the neutron star maximum mass of about 1.45 Msun to be 0.4--0.5 Msun lower than the prediction by using the other choices for hyperon couplings.[第一段]     

Effect of momentum anisotropy on quark matter in the quark-meson model

We investigate the chiral phase structure of quark matter with spheroidal momentum-space anisotropy specified by one anisotropy parameter ξ in the 2+1 flavor quark-meson model.We find that the chiral phase diagram and the location of the critical endpoint(CEP) are significantly affected by the value of ξ.With an increase inξ,the CEP is shifted to lower temperatures and higher quark chemical potentials.In addition,the temperature of the CEP is more sensitive to the anisotropy parameter than the corresponding quark chemical potential,which is the opposite to that from the finite system volume effect.The effects of the momentum anisotropy on the thermodynamic properties and scalar(pseudoscalar) meson masses are also studied at the vanishing quark chemical potential.The numerical results reveal that an increase in ξ can hinder the restoration of chiral symmetry.We also find that shear viscosity and electrical conductivity decrease as ξ increases.However,the bulk viscosity exhibits a significant nontrivial behavior with ξ in the entire temperature domain of interest.     

Deconfinement Phase Transition Including Perturbative QCD Corrections in （Proto）neutron Star Matter

Deconlinement phase transition and neutrino trapping in （proto）neutron star matter are investigated in a chiral hadronic model （also referred to as the FST model） for the hadronic phase （HP） and in the color-flavor-locked （CFL） quark model for the deconlined quark phase. We include a perturbative QCD correction parameter αs in the CFL quark matter equation of states. It is shown that the CFL quark core with K^0 condensation forms in neutron star matter with the large value of αs. If the small value of αs is taken, hyperons suppress the CFL quark phase and the liP is dominant in the high-density region of （proto）neutron star matter. Neutrino trapping makes the fraction of the CFL quark matter decrease compared with those without neutrino trapping. Moreover, increasing the QCD correction parameter as or decreasing the bag constant B and the strange quark mass ms can make the fraction of the CFL quark matter increase, simultaneously, the fraction of neutrino in protoneutron star matter increases, too. The maximum masses and the corresponding radii of （proto）neutron stars are not sensitive to the QCD correction parameter αs.     

Dispersion relation of excitation mode in strongly interacting fermions matter

This paper analyses the dispersion relation of the excitation mode in non-relativistic interacting fermion matter. The polarization tensor is calculated with the random phase approximation in terms of finite temperature field theory. With the polarization tensor, the influences of temperature, particle number density and interaction strength on the dispersion relation are discussed in detail. It finds that the collective effects are qualitatively more important in the unitary fermions than those in the finite contact interaction matter.     

η-nucleus bound states in nuclei

The binding energies η and widths Γη of η-mesic nuclei are calculated.We parameterize the η self-energy in the nuclear medium as a function of energy and density.We find that the single-particle energies are sensitive to the scattering length,and increase monotonically with the nucleus.The key point for the study of η-nucleus bound states is the η-nuclear optical potential.We study the s-wave interactions of η mesons in a nuclear medium and obtain the optical potential Uη≈ -72 MeV.Comparing our results with the previous results,we find that the ηN scattering length aηN is indeed important to the calculations.With increasing nuclear density the effective mass of the η meson decreases.     

η-nucleus bound states in nuclei

The binding energies εη and widths Гη of wmesic nuclei are calculated. We parameterize the η self-energy in the nuclear medium as a function of energy and density. We find that the single-particle energies are sensitive to the scattering length, and increase monotonically with the nucleus. The key point for the study of η-nucleus bound states is the η-nuclear optical potential. We study the s-wave interactions of η mesons in a nuclear medium and obtain the optical potential Uη ≈ -72 MeV. Comparing our results with the previous results, we find that the ηN scattering length aηN is indeed important to the calculations. With increasing nuclear density the effective mass of the η meson decreases.