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Hadronic Phases in High-Density Nuclear Matter and Neutron Stars

高密度核物质和中子星的强子相

基本信息

批准号：
12640289
负责人：
MUTO Takumi
金额：
$ 2.56万
依托单位：
Chiba Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640289/
关键词：
high-density matter neutron star kaon condensation hyperon p-wave interaction equation of state metastable state self-bound state 粒子-空孔励起分散関係形状因子分散式

项目摘要

Possible existence of kaon condensation in hyperonic matter, where hyperons are mixed in the ground state of neutron-star matter, has been investigated. P-wave kaon-baryon interactions are included as well as s-wave ones by the use of the SU(3) xSU(3) effective chiral Lagrangian. Baryonic potentials in high-density matter are also taken into account through the nonrelativistic effective baryon-baryon interactions which are based on the recent information from hypernuclear experiments. (1) The dispersion relations of kaons have been obtained. It has been shown that there appears an instability with respect to a pair creation of collective particle-hole modes with K^+ and K^-quantum numbers, stemming from the p-wave kaon-baryon interaction. The onset density of this instability is lower than that of the s-wave K^-condensation. (2) The equation of state (EOS) of the kaon-condensed phase has been studied, and the effects of the EOS on the static properties of neutron stars have been discussed. It has been shown that in the fully-developed phase, the effects of p-wave interactions are small, and that kaon condensation becomes of the s-wave type at higher density. The EOS becomes very soft owing to the s-wave kaon-baryon interactions. In addition to the kaon-condensed branch with a first-order phase transition after Maxwell's construction, there is a kaon-condensed 'self-bound' branch just like a self-bound state for a strange star. The whole star is composed of kaon condensates with high-density. The self-bound star contains a metastable region, so that it eventually decays into a stable star obtained with Maxwell's construction with the total baryon number fixed. The lifetime of the kaon-condensed self-bound star has been estimated in a semi-classical approximation. It is possible that the lifetime is longer than the age of the universe, so that the self-bound star is substantially stable.

研究了在中子星物质基态中混合超子的超子物质中K介子凝聚的可能性。利用SU（3）xSU（3）有效手征拉格朗日量，不仅包括了s波相互作用，也包括了p波K介子-重子相互作用。基于超核实验的最新信息，通过非相对论性的重子-重子有效相互作用，考虑了高密度物质中的重子势。(1)得到了K介子的色散关系。研究表明，在p波K介子-重子相互作用中，产生一对具有K^+和K^-量子数的粒子-空穴集体模时，会出现不稳定性。这种不稳定性的起始密度低于s波K^-凝聚的起始密度。(2)研究了K介子凝聚相的物态方程，讨论了物态方程对中子星静态性质的影响。结果表明，在充分发展阶段，p波相互作用的影响很小，和K介子凝聚成为s波型在较高的密度。由于s波的K介子-重子相互作用，物态方程变得很软。除了麦克斯韦构造后的一级相变的K介子凝聚分支外，对于奇异星星，还存在一个类似于自束缚态的K介子凝聚“自束缚”分支。整个星星由高密度的K介子凝聚体组成。自束缚的星星包含一个亚稳区，因此它最终衰变为一个稳定的星星，这是用麦克斯韦的结构得到的，总的重子数是固定的。在半经典近似下，估计了K介子凝聚自束缚星星的寿命。有可能它的寿命比宇宙的年龄还长，因此自约束的星星是相当稳定的。