Magnetic dipole (M1) excitation is the leading mode of multi-nucleon excitations induced by the magnetic field, and is a phenomenon of the spin–orbit splitting and residual interactions involved. In this work, we investigate the effects of the residual interactions on the M1 excitation from a novel perspective, the framework of relativistic nuclear energy-density functional. The relativistic Hartree–Bogoliubov model is utilized to determine the nuclear ground state properties, while the relativistic quasi-particle random-phase approximation is employed for the description of M1-excitation properties. From the analysis of M1 mode in the Ca isotope chain, role of the isovector–pseudovector residual interaction is discussed. For open-shell nuclei, the pairing correlation also plays a noticeable role in the M1 mode. The experimental data on M1 mode is expected to provide a suitable reference to improve and optimize the theoretical models to describe the residual interactions.

中文翻译：

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残余相互作用在M1激发的相对论描述中的作用

磁偶极子（M1）激发是磁场诱导的多核子激发的主导模式，并且是自旋轨道分裂和残余相互作用的一种现象。在这项工作中，我们从相对论核能密度函数的新观点研究了残留相互作用对M1激发的影响。相对论的Hartree–Bogoliubov模型用于确定核基态性质，而相对论的准粒子随机相近似用于描述M1激发性质。通过分析Ca同位素链中的M1模式，讨论了等矢量-伪矢量残余相互作用的作用。对于开壳核，配对相关在M1模式下也起着明显的作用。