Orbital and spin scissors modes in superfluid nuclei

TL;DR

This paper extends the theoretical framework for nuclear scissors modes by incorporating spin degrees of freedom and pair correlations, revealing a new source of nuclear magnetism and improving agreement with experimental data.

Contribution

It introduces a generalized Wigner function moments method that accounts for spin and pairing, discovering a new nuclear magnetism source and enhancing predictive accuracy.

Findings

Identification of a new nuclear magnetism source linked to spin counter-rotation.

Improved theoretical predictions of energies and transition probabilities.

Better alignment with experimental data for rare earth nuclei.

Abstract

Nuclear scissors modes are considered in the frame of Wigner function moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes in rare earth nuclei.