AI 中文总结
该研究探讨含超子和Δ共振的中子星物质中，密度诱导的中子向暗重子χ的自洽转换，发现超子和Δ会抑制χ丰度，且χ质量影响恒星最大质量，需同等考虑非核子自由度与暗重子。
AI 中文摘要
我们在包含超子和全部Δ(1232)四重态的冷、电中性、β平衡的中子星物质中，研究密度诱导的中子向中性暗重子χ的转换。强子部分采用密度依赖的协变密度泛函框架，使用DDME2参数化进行建模。我们纳入标量希格斯门户作为可见 sector 与暗 sector 之间的可能相互作用通道，不过对于本文采用的耦合，其平均场贡献可忽略不计。与固定暗物质混杂模型或核子向暗物质转换由希格斯交换驱动的场景不同，χ的丰度由化学平衡和重子数守恒自洽确定。我们发现，超子和Δ共振会改变中子化学势，延迟χ的出现，并相对于核子物质抑制其丰度。这种竞争会在物态方程、粒子分数、声速和绝热指数中引发特征性变化。对于m_χ=1250、1300和1400 MeV，完整的N+Y+Δ+χ构型的最大质量分别为1.806、1.899和2.024 M_⊙，这表明大质量脉冲星的约束不利于较轻的暗重子基准。径向分布进一步显示，对于m_χ=1400 MeV，χ被限制在最大质量恒星的内核心，而典型构型基本不受影响。因此，恒星的修改主要源于转换诱导的平衡组成重排，而非希格斯介导的相互作用。这些结果强调，在评估致密物质暗 sector 扩展的天体物理可行性时，同等对待常规非核子自由度和密度生成的暗重子具有重要意义。
英文摘要
We investigate density-induced conversion of neutrons into a neutral dark baryon $χ$ in cold, charge-neutral, $β$-equilibrated neutron-star matter containing hyperons and all $Δ(1232)$ quartet. The hadronic sector is modeled within a density-dependent covariant density-functional framework using the DDME2 parametrization. A scalar Higgs portal is included as a possible interaction channel between the visible and dark sectors, although its mean-field contribution is negligible for the couplings adopted here. Unlike fixed dark-matter admixture models or scenarios in which nucleon-to-DM conversion is driven by Higgs exchange, the $χ$ abundance is determined self-consistently from chemical equilibrium and baryon-number conservation. We find that hyperons and $Δ$ resonances alter the neutron chemical potential, delay the onset of $χ$, and suppress its abundance relative to nucleonic matter. This competition induces characteristic changes in the equation of state, particle fractions, sound speed, and adiabatic index. For $m_χ=1250$, $1300$, and $1400$ MeV, the maximum masses of the complete $N+Y+Δ+χ$ configurations are $1.806$, $1.899$, and $2.024,M_\odot$, respectively, indicating that the massive-pulsar constraint disfavors the lighter dark-baryon benchmarks. The radial profiles further show that for $m_χ=1400$ MeV, $χ$ is confined to the inner core of the most massive stars, while canonical configurations remain essentially unaffected. Thus, the stellar modifications arise primarily from conversion-induced rearrangement of the equilibrium composition rather than from Higgs-mediated interactions. These results highlight the importance of treating conventional non-nucleonic degrees of freedom and density-generated dark baryons on an equal footing when assessing the astrophysical viability of dark-sector extensions of dense matter.
Comments18 pages, 8 figures. Comments are welcome
