标题： 从π介子平均场方法看中子星和混含奇异性星的性质 显示英文标题

标题： Properties of neutron stars and strangeness-mixed stars from a pion mean-field approach

摘要： 我们基于从π介子平均场方法推导出的状态方程，研究了静态中子星和混有奇异性星的性质。利用π介子-原子核散射和核物质整体性质的经验数据，我们在之前的工作中已经固定了所有参数，在该工作中展示了在各种核介质中，核子和超子会被修正。在当前的工作中，我们首先检查了中子星内部的能量和压力。我们表明，各种中子星的中心密度在$(3-6)\rho_0$的范围内变化，其中$\rho_0$是正常核物质密度。获得了质量-半径关系并进行了讨论。随着中子物质斜率参数的增加，固定质量的中子星半径也随之增加。我们还使用相同的参数集研究了混有奇异性星或超子星。随着奇异性物质的奇异性含量增加，每个核子的结合能趋于饱和，相应的状态方程变软。因此，混有奇异性星的中心密度增加。假设最近观测到的中子星是混有奇异性星，我们发现其中心密度增加。在纯奇异性星的情况下，中心密度几乎达到$(5-6)\rho_0$。 显示英文摘要

摘要： We investigate the properties of the static neutron stars and strangeness-mixed stars, based on the equations of state derived from a pion mean-field approach. Using the empirical data on the pion-nucleus scattering and bulk properties of nuclear matter, we have already fixed all the parameters in a previous work, where the nucleons and hyperons were shown to be modified in various nuclear medium. In the current work, we first examine the energy and pressure inside a neutron star. We show that the central densities in various neutron stars vary within the range of $(3-6)\rho_0$, where $\rho_0$ is the normal nuclear matter density. The mass-radius relations are obtained and discussed. As the slope parameter for neutron matter increases, the radii of the neutron stars increase with their masses fixed. We also study the strangeness-mixed stars or the hyperon stars using the same sets of the parameters. As the strangeness content of strange matter increases, the binding energy per nucleon is saturated and the corresponding equation of state becomes softened. Consequently, the central densities of the strangeness-mixed stars increase. Assuming that recently observed neutron stars are the strangeness-mixed ones, we find that the central densities increase. In the case of the pure strange stars, the central densities reach almost $(5-6)\rho_0$.