摘要:
基于相对论平均场理论,系统地研究了单Λ,Ξ 和Σ 超核,超子-核子相互作用通过拟合实验数据以及参照之前理论工作来确定.以16O为核芯,通过加入不同类型超子(Λ,Ξ0,- 和Σ+,0,-),比较了超子的平均势场和单粒子能级,并研究了对核芯的杂质效应.整体上看,Λ和Ξ0 超子在大块性质上类似;Ξ0 超子平均势场最浅;库仑相互作用对于带电超子Ξ-,Σ+ 和Σ-非常重要.作为杂质,原子核中加入超子会使整个体系更束缚.然而,不同超子对原子核的半径有不同效应.此外,讨论了ωYY 张量耦合,发现其对超子的能级劈裂有显著影响,甚至导致Ξ超子中出现能级反转现象.
Abstract:
Single Λ, Ξ, and Σ hypernuclei are systematically studied within the framework of relativistic mean-field (RMF) model with YN interactions being constrained according to the experimental data and previous theoretical efforts. By adding a hyperon to 16O, the mean-field potentials and single-particle levels for hyperons (Λ, Ξ0,-, and Σ+,0,-) are compared and the impurity effects on the nuclear core are examined. In general, the Λ and Σ0 hyperons show similar behaviors in bulk properties since both of them are electroneutral and with similar coupling constants; Ξ0 hyperon owns the shallowest mean-field potential well; and Coulomb interactions play vital roles in the charged Ξ-, Σ-, and Σ+ hyperons. As an impurity, the intruded single-hyperon makes the nuclear system more bound in most cases due to the attractive NY interaction. However, very different effects on the nucleon radii are observed for different hyperons. Besides, the effects of the ωYY tensor couplings on the spin-orbit splitting are discussed, and remarkable influences are found which even change the level ordering of Ξ hyperon.
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