Spin Scissors Mode and the Fine Structure of M1 States in Nuclei

TL;DR

This paper investigates the interplay of low-lying collective nuclear modes, including the scissors mode, with giant quadrupole resonances using a spin-inclusive Wigner Function Moments approach, revealing new spin-dependent nuclear motions.

Contribution

It introduces a generalized Wigner Function Moments method incorporating spin to analyze coupled nuclear collective modes and their fine structure.

Findings

Identification of new spin-dependent nuclear oscillations

Derivation of equations of motion for collective variables with spin

Enhanced understanding of M1 state fine structure

Abstract

The coupled dynamics of low lying modes, including the scissors mode, and various giant quadrupole resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom. Equations of motion for collective variables are derived on the basis of Time Dependent Hartree-Fock equations in the model of harmonic oscillator with spin orbital mean field potential plus quadrupole-quadrupole residual interaction. Introducing spin allows one to consider new types of nuclear collective motion where the nucleons with spin 'up' oscillate against nucleons with spin 'down'.