Magnetic dipole (M1) excitations build not only a fundamental mode of nucleonic transitions, but they are also relevant for nuclear astrophysics applications. We have established a theory framework for description of M1 transitions based on the relativistic nuclear energy density functional. For this purpose the relativistic quasiparticle random phase approximation (RQRPA) is established using density dependent point coupling interaction DD-PC1, supplemented with the isovector-pseudovector interaction channel in order to study unnatural parity transitions. The introduced framework has been validated using the M1 sum rule for core-plus-two-nucleon systems, and employed in studies of the spin, orbital, isoscalar and isovector M1 transition strengths, that relate to the electromagnetic probe, in magic nuclei ${}^{48}$Ca and ${}^{208}$Pb, and open shell nuclei ${}^{42}$Ca and ${}^{50}$Ti. In these systems, the isovector spin-flip M1 transition is dominant, mainly between one or two spin-orbit partner states. It is shown that pairing correlations have a significant impact on the centroid energy and major peak position of the M1 mode. The M1 excitations could provide an additional constraint to improve nuclear energy density functionals in the future studies.

中文翻译：

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基于相对论核能密度泛函的磁偶极子激发

磁偶极子（M1）激发不仅建立了核子跃迁的基本模式，而且还与核天体物理学应用相关。我们建立了一个基于相对论核能密度泛函描述M1跃迁的理论框架。为此，使用密度相关的点耦合相互作用DD-PC1并建立了等矢量-伪矢量相互作用通道，建立了相对论的准粒子随机相位近似（RQRPA），以研究非自然的奇偶性跃迁。引入的框架已使用M1和规则对核心加两个核子系统进行了验证，并用于研究魔核中与电磁探针有关的自旋，轨道，等量和等矢量M1跃迁强度。${}^{48}$钙和 ${}^{208}$铅和开壳核 ${}^{42}$钙和 ${}^{50}$钛 在这些系统中，等矢量自旋翻转M1过渡是主要的，主要在一个或两个自旋轨道伙伴状态之间。结果表明，配对相关性对质心能量和M1模式的主要峰位置有重大影响。在未来的研究中，M1激发可能会为改善核能密度功能提供额外的限制。