论文标题
中子星中的三角洲重子
Delta baryons in neutron stars
论文作者
论文摘要
通过与密度依赖性耦合的中子恒星物质的相对论均值场描述，我们分析了两种不同物质组成的特性：用delta baryons和hyperons和delta baryons的核心物质和核次物质。允许Delta-Meson耦合在通过实验数据获得的宽范围内变化，而Hyperon-Meson耦合则拟合到超核特性。研究了没有解反性相变的中子星特性。可以验证许多模型被排除在外，因为在达到最大质量构型之前，有效的核子质量变为零。可以使用Deltic恒星的Deltto恒星，无效的Delta主导组合物紧凑型恒星。据发现，有了方便的参数选择，可以使用恒星80％的Deltic恒星存在于恒星中心。然而，在中心的饱和密度下，超子的存在降低了三角洲巴属的分数至中心低于20％的值，低于30％。讨论的是，在有三角洲重子的存在下，超子软化并不是那么剧烈，因为Deltas夫妇对$ω$ -Meson更强烈，并且状态方程的刚度是由高密度下的$ω$ dominance确定的。声音的速度反映了这种行为。 PULSAR RX J0720.4-3125的紧凑性强加了$ x_ {σδ}> x_ {ωΔ}> 1 $，并有利于$ x_ {ρδ}> 1 $。
By applying a relativistic mean-field description of neutron star matter with density dependent couplings, we analyse the properties of two different matter compositions: nucleonic matter with delta baryons and nucleonic matter with hyperons and delta baryons. The delta-meson couplings are allowed to vary within a wide range of values obtained by experimental data, while the hyperon-meson couplings are fitted to hypernuclear properties. Neutron star properties with no deconfinement phase transition are studied. It is verified that many models are excluded because the effective nucleon mass becomes zero before the maximum mass configuration is attained. Hyperon-free with delta-dominated composition compact stars are possible, the deltic stars. It is found that with a convenient choice of parameters the existence of deltic stars with 80% of delta baryons at the center of the star is possible. However, the presence of hyperons lowers the delta baryon fraction to values below 20% at the center and below 30% at 2-3 saturation densities. It is discussed that in the presence of delta baryons, the hyperon softening is not so drastic because deltas couple more strongly to the $ω$-meson, and the stiffness of the equation of state is determined by the $ω$-dominance at high densities. The speed of sound reflects very well this behavior. The compactness of the pulsar RX J0720.4-3125 imposes $x_{σΔ}>x_{ωΔ}>1$ and favors $x_{ρΔ}>1$.
