Radiative decay and electromagnetic moments in $^{229}$Th determined within nuclear DFT

TL;DR

This study uses nuclear density functional theory to analyze electromagnetic properties and moments of $^{229}$Th, providing insights into parity breaking, configuration mixing, and the need for improved functional parametrizations.

Contribution

It applies symmetry-breaking and restoration within nuclear DFT to predict electromagnetic moments and transition strengths in $^{229}$Th without parameter adjustment.

Findings

Results agree with experimental data for magnetic and electric moments.

Analysis highlights the importance of octupole degrees of freedom in functional parametrizations.

Comparison across multiple Skyrme functionals suggests systematic adjustments are needed.

Abstract

Using the nuclear DFT approach with symmetry breaking and restoration, we investigate the electromagnetic properties of the ground and isomeric states in $^{229}$Th. We determine the magnetic dipole transition strength B(M1; $3/2^+_1\rightarrow 5/2^+_1)$ between these two states and discuss the effects of parity breaking, configuration mixing, and time-odd core polarization. We also determine the corresponding spectroscopic magnetic dipole and octupole, and electric quadrupole moments. Because the octupole deformability of the Skyrme functionals used here is not described in sufficient detail, we analyze the results using a set of Skyrme functionals and perform a regression aligned with the measured electric octupole moments of neighboring even-even nuclei. Without parameter adjustment, the results compare favorably with the experimental data but also indicate the need to systematically adjust the octupole degrees of freedom in future functional parametrizations.