In the framework of the relativistic mean field theory, the neutrino emission from the baryonic direct URCA processes and nucleonic modified URCA processes in neutron star (NS) matter is investigated. We discuss particularly the influence of the extension of the SU(6) spin-flavor symmetry to the SU(3) flavor symmetry on the sizes of the neutrino energy losses, baryonic density and mass ranges of the above neutrino emission processes. In the nucleonic direct URCA processes, the neutrino energy losses in NS matter consisted of npeμ are observably higher than these in NS matter involving hyperons. For NS matter involving hyperons, the neutrino energy losses with the SU(3) flavor symmetry are slightly lower than those with the SU(6) spin-flavor symmetry. In the hyperonic direct URCA processes, the neutrino energy losses for the reactions of Λ → p + l + ν̄l and Ξ−→ Λ + l + ν̄ l with the SU(3) flavor symmetry are obviously smaller than these with the SU(6) spin-flavor symmetry. However, the neutrino energy loss of the reaction of Ξ−→ Ξ0 + e + ν̄ e with the SU(3) flavor symmetry is observably higher than that with the SU(6) spin-flavor symmetry. Moreover, the threshold densities of processes for Ξ−→ Ξ0 + e + ν̄ e with the SU(3) flavor and SU(6) spin-flavor symmetries are 0.868fm−3 and 0.806fm−3 (corresponding to 2.118M⊙ and 1.838M⊙), respectively, which mean that it only happens in the interior of the massive NSs. For the neutron and proton branch modified URCA processes, the neutrino emission rates with the SU(3) flavor symmetry are also less than those with the SU(6) spin-flavor symmetry.

中文翻译：

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重子-重子相互作用对重子直接 URCA 过程和中子星物质中核子修正 URCA 过程的中微子发射的影响

在相对论平均场理论的框架下，研究了中子星（NS）物质中重子直接URCA过程和核子修饰URCA过程的中微子发射。我们特别讨论了将 SU(6) 自旋味对称性扩展到 SU(3) 味对称性对上述中微子发射过程的中微子能量损失、重子密度和质量范围的大小的影响。在核子直接 URCA 过程中，NS 物质中的中微子能量损失包括npeμ在涉及超子的NS物质中明显高于这些。对于超子的NS物质，具有SU(3)味对称性的中微子能量损失略低于具有SU(6)自旋味对称性的中微子能量损失。在高超声速直接 URCA 过程中，中微子反应的能量损失Λ → p + l + ν̄l和Ξ-→ Λ + l + ν̄ lSU(3) 风味对称性明显小于 SU(6) 自旋风味对称性。然而，中微子反应的能量损失Ξ-→ Ξ0 + e + ν̄ eSU（3）风味对称性明显高于SU（6）自旋风味对称性。此外，过程的阈值密度Ξ-→ Ξ0 + e + ν̄ eSU(3) 风味和 SU(6) 自旋风味对称性为 0.868调频-3和 0.806调频-3（对应于 2.118米⊙和 1.838米⊙)，这意味着它只发生在大规模 NS 的内部。对于中子和质子分支修改的URCA过程，具有SU（3）味对称性的中微子发射率也小于具有SU（6）自旋味对称性的中微子发射率。