Why do Nilsson quantum numbers remain good at moderate deformations?

TL;DR

This paper explains why Nilsson quantum numbers remain valid at moderate nuclear deformations, attributing this to an underlying approximate symmetry called proxy-SU(3), which influences nuclear structure interpretations.

Contribution

It reveals that the persistence of Nilsson quantum numbers at moderate deformations is due to the proxy-SU(3) symmetry, providing a new understanding of nuclear structure.

Findings

Nilsson quantum numbers stay valid at moderate deformations

Proxy-SU(3) symmetry underpins the robustness of quantum labels

Implications for nuclear structure models and interpretations

Abstract

The Nilsson model is a simple microscopic model which has been extensively used over the years for the interpretation of a bulk of experimental results. The single particle orbitals in this model are labeled by quantum numbers which are good in the limit of large nuclear deformations. However, it is generally admitted that these quantum numbers remain good even at moderate deformations. We show that this fact is due to the existence of an underlying approximate symmetry, called the proxy-SU(3) symmetry. The implications of proxy-SU(3) on various aspects of nuclear structure will be discussed.