Nuclear scissors modes and hidden angular momenta

TL;DR

This paper investigates nuclear scissors modes and hidden angular momenta using an advanced Wigner Function Moments method, revealing a new source of nuclear magnetism that improves agreement with experimental data.

Contribution

It introduces a generalized Wigner Function Moments approach incorporating spin and pair correlations, and uncovers a new nuclear magnetism source linked to hidden angular momenta.

Findings

Discovery of a new nuclear magnetism source from counter-rotating spins.

Enhanced theoretical agreement with experimental energies and transition probabilities.

Analysis of low lying spin-dependent modes, especially scissors modes.

Abstract

The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. The method is based on Time Dependent Hartree-Fock-Bogoliubov equations. The model of the harmonic oscillator including spin-orbit potential plus quadrupole-quadrupole and spin-spin interactions is considered. New low lying spin dependent modes are analyzed. Special attention is paid to the scissors modes. 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.