Relativistic energy-density functional approach to magnetic-dipole excitation and its sum rule

TL;DR

This paper develops a relativistic energy density functional approach to study magnetic-dipole excitations in nuclei, successfully reproducing experimental data and providing a systematic framework for analyzing M1 modes across different nuclei.

Contribution

The paper introduces a relativistic nuclear energy density functional framework combined with RPA for systematic M1 excitation analysis in nuclei.

Findings

The method reproduces M1 sum rule values for $^{18}$O and $^{42}$Ca.

Results agree with experimental data for $^{208}$Pb within quenching factor considerations.

The framework offers a consistent approach for M1 excitation studies.

Abstract

Magnetic-dipole (M1) excitations of $^{18}$O and $^{42}$Ca nuclei are investigated within a relativistic nuclear energy density functional framework. In our last work \cite{2019OP}, these nuclei are found to have unique M1 excitation and its sum rule, because of their characteristic structure: the system consists of the shell-closure core plus two neutrons. For a more systematic investigation of the M1 mode, we have implemented a framework based on the relativistic nuclear energy density functional (RNEDF). For benchmark, we have performed the RNEDF calculations combined with the random-phase approximation (RPA). We evaluate the M1 excitation of $^{18}$O and $^{42}$Ca, whose sum-rule value (SRV) of the M1 transitions can be useful to test the computational implementation \cite{2019OP}. We also apply this RNEDF method to $^{208}$Pb, whose M1 property has been precisely measured \cite{1979Holt,1987Koehler,1988Laszewski,2016Birkhan}. Up to the level of the M1 sum rule, our result is in agreement with the experiments, except the discrepancy related with the quenching factors for $g$ coefficients.