第一性原理研究三体力对^(28)F和^(29)Ne低激发谱的影响  

Effects of three-nucleon force on the low-lying states of ^(28)F and ^(29)Ne within ab initio calculations

作　　者：戴博 李健国 张爽[1] 王思敏 许甫荣[1] Bo Dai;Jianguo Li;Shuang Zhang;Simin Wang;Furong Xu(School of Physics,Peking University,Beijing 100871,China)

机构地区：[1]北京大学物理学院,北京100871

出　　处：《科学通报》2021年第30期3866-3872,共7页Chinese Science Bulletin

基　　金：国家重点研发计划(2018YFA0404401);国家自然科学基金(11835001,12035001,11921006)资助。

摘　　要：从手征有效场论的N^(3)LO两体和N^(2)LO三体核力出发,采用第一性原理方法(开壳原子核多体微扰理论)计算了^(28)F和^(29)Ne的低激发能谱,并以此研究手征三体力对反转岛区域原子核性质的影响.通过对比采用纯两体与两体加三体力计算的^(28)F和^(29)Ne的低激发能谱,发现手征三体力对反转岛内原子核基态宇称反转现象有着重要的贡献.为了进一步探究三体力的影响,系统计算了丰中子Ne同位素的偶偶核基态波函数中的组态成分.结果显示,三体力显著地加强了跨壳激发效应,使理论计算与实验结果更加符合.One of the most interesting anomalies in nuclear physics is the island of inversion(IOI),which indicates that the magic numbers disappear.It provides a good platform to understand single-particle motion,many-body correlation,and nucleonnucleon interaction.In neutron-rich isotopes near N=20 area,many experiments have found that the spectra,electromagnetic transitions,radii,and two-neutron separation energies of these nuclei are abnormal.This region is called the N=20 IOI,because it is characterized by neutron particle-hole excitations related to deformation from the 1s0d shell into the 1p0f shell across the N=20 shell gap.Recent experiments show that the ground states of ^(29)Ne and ^(28)F have negative parities,indicating that these two nuclei are within the N=20 IOI.This provides new opportunities and challenges for theoretical models in this area.With the standard shell model,the N=20 IOI has been proved by many works to have a strong cross-shell effect between1s0d and 1p0f shells.They proposed that the tensor force and three-nucleon force should have an important influence on the microscopic description of neutron-rich nuclei in this area,especially in Ne and Mg isotopes.However,the N=20 IOI is still rarely studied in ab initio calculations.Recently,an extension of the ab initio valence-space in-medium similarity renormalization group method was presented to study the physics of neutron-rich nuclei by Miyagi et al.In the present paper,based on chiral force including nucleon-nucleon and three-nucleon force,we have performed ab initio calculations for the low-lying states of ^(28)F and ^(29)Ne,focusing on the relative excitation energies of the positive-and negative-parity states in these nuclei.In order to study the effect of three-nucleon force on the N=20 IOI,we use nucleonnucleon force at N^(3)LO with or without three-nucleon force at N^(2)LO in our calculations.Using the open-shell many-body perturbation theory,the cross shell sd-pf realistic effective Hamiltonian,including single-particle energies and effe

关 键 词：手征核力 第一性原理计算 三体力 反转岛 

分 类 号：O571[理学—粒子物理与原子核物理]