论文标题
Gamow-Teller和磁极转变的对称破坏及其在钙同位素中的恢复
Symmetry breaking of Gamow-Teller and magnetic-dipole transitions and its restoration in calcium isotopes
论文作者
论文摘要
核磁 - 偶极子（M1）和Gamow-Teller（GT）过渡提供了对原子核的自旋形成性质的见解。通过将它们视为统一的自旋旋转过渡，M1/GT的过渡强度和激发能可以受到同胞对称性的影响。需要在一致的理论方法中阐明与M1/GT对称性相关的激发属性。在这项工作中，使用相对论的准论准颗粒随机相近似（RQRPA），基于相对论的能量密度功能（REDF）与点耦合相互作用的统一框架中研究了Ca同位素中M1和GT转变之间的关系。结果表明，在封闭壳核中，这种相互作用破坏了ISOVECTOR-PESUDOVECTOR（IV-PV）残留相互作用，M1和Giant-GT转变的对称性都会破坏M1和Giant-GT转变的对称性。在开放壳Ca同位素中，残留RQRPA相互作用中的质子独立配对也在GT转变中起作用。由于这些相互作用之间的相互作用，可以恢复M1/GT对称性，尤其是在$^{42} $ CA核中，即，巨型GT强度可以通过统一的旋转式旋转式过渡来调节实验性低效果的巨型旋转旋转强度与M1模式相媲美。还为开放式镜像合作伙伴，$^{42} $ ca和$^{42} $ ti展示了M1和GT转换的镜像对称性。需要进一步的改进来实现REDF框架中M1和GT转换能的同时再现。
Nuclear magnetic-dipole (M1) and Gamow-Teller (GT) transitions provide insight into the spin-isospin properties of atomic nuclei. By considering them as unified spin-isospin transitions, the M1/GT transition strengths and excitation energies are subject to isospin symmetry. The excitation properties associated to the M1/GT symmetry need to be clarified within consistent theoretical approach. In this work, the relationship between the M1 and GT transitions in Ca isotopes is investigated in a unified framework based on the relativistic energy-density functional (REDF) with point-coupling interactions, using the relativistic quasi-particle random-phase approximation (RQRPA). It is shown that the isovector-pseudovector (IV-PV) residual interaction affects both transitions, and the symmetry of M1 and giant-GT transitions is disrupted by this interaction in closed-shell nuclei. In open-shell Ca isotopes, the proton-neutron pairing in the residual RQRPA interaction also plays a role in GT transitions. Due to the interplay between these interactions, the M1/GT symmetry can be restored especially in the $^{42}$Ca nucleus, i.e., the giant-GT strength can become comparable to that of the M1 mode in terms of the unified spin-isospin transitions by adjusting the PN-pairing strength to reproduce the experimental low-lying GT-excitation energies. The mirror symmetry of both M1 and GT transitions is also demonstrated for open-shell mirror partners, $^{42}$Ca and $^{42}$Ti. Further improvements are required to achieve simultaneous reproduction of M1 and GT-transition energies in the REDF framework.
