低密核物质与奇特原子核中的双中子关联现象

Based on the relativistic continuum Hartree-Bogoliubov theory and the relativistic Hartree-Fock-Bogoliubov theory, the di-neutron correlations in low-density nuclear matter as well as in exotic nuclei will be systematically investigated in this project. The properties of pairing correlations in nuclear matter and the corresponding density-dependent or pairing strength-dependent behaviors will be studied in order to find characteristic quantities and microscopic physical mechanisms for deciding the strength of the di-neutron correlations. The possibility that a strong correlated di-neutron bound state appears in a low-density nuclear matter will be discussed as well. Then a systematical study on the di-neutron correlations will be carried out in neutron-rich nuclei. The relation between the di-neutron correlations and the halo structure of exotic nuclei, and the role of di-neutron correlations in keeping the stability of the structure of weakly-bound nuclei will be investigated in detail. Whether a strong di-neutron correlated nucleus could be found in medium or heavy nuclei is an interesting question to be clarified. Moreover, the influence of several meson coupling channels of the Fock terms and the corresponding tensor part on the di-neutron correlation behaviors will be studied in the relativistic Hartree-Fock-Bogoliubov calculations. It is expected that such a project will be helpful to understand the effect of the residual interaction of nuclear force in nuclear many-body system, and provide valuable theoretical information for the microscopic properties of nuclear force.

本项目拟基于相对论连续谱Hartree-Bogoliubov理论和相对论Hartree-Fock-Bogoliubov理论，系统研究低密度核物质与奇特原子核中的双中子关联现象。通过研究核物质对关联属性的密度及对力依赖行为，确定影响双中子关联强弱的微观物理机制及其特征物理判据，探索低密度核物质中出现强关联的双中子束缚态的可能性；通过研究丰中子原子核中的双中子空间关联行为，探索双中子关联与奇特原子核晕现象之间可能的联系，确定其对于弱束缚原子核结构稳定性所起的作用，并在中重质量原子核区域寻找具有双中子空间强关联特征的代表性原子核；基于相对论Hartree-Fock-Bogoliubov理论，进一步研究交换项各耦合道特别是张量耦合部分对于双中子关联现象以及奇特原子核结构稳定性的影响。由此，为深入理解核力的剩余相互作用在原子核系统中的效应及定量理解核力的微观属性提供参考。

本项目基于协变密度泛函（CDF）理论，包括相对论Hartree-Bogoliubov理论和相对论Hartree-Fock-Bogoliubov理论等，研究了低密度核物质与奇特原子核中的双中子关联现象及相关物理。在核物质中，采用Gogny对力和适用于CDF理论的新判据条件，预测了发生BCS-BEC crossover的密度范围，计算显示双中子BEC束缚态难以在核物质中出现。基于Brueckner理论，考虑核力短程关联效应，研究了高密度中子物质的中子超流现象。在有限原子核中，系统性研究了轻核到重核区原子核结合能的奇偶振荡，通过拟合实验结果给出了对力强度的核子数依赖关系。进一步，开展了轻核区碳同位素链基态性质的系统性研究，发现在接近中子滴线时碳原子核的中子半径出现奇偶振荡现象，预测了可能存在中子晕结构的候选原子核。在含交换项的CDF理论基础上，发展了原子核张量力的相对论协变公式。基于该公式，在相对论模型中实现了对核力中张量相互作用与自旋-轨道相互作用的统一自洽描述。此外还研究了核物质对称能物理中的交换项效应，发现交换项的引入降低了对称能的动能部分贡献，在一定密度区域贡献甚至为负值，而该效应部分地来自于交换项中自洽包含的张量力贡献。项目研究结果为深入理解核力的剩余相互作用在原子核多体系统中的效应以及定量理解核力的微观属性提供了参考。