The Spin Orbit term in the Nuclear Shell Model

TL;DR

This paper investigates the origin and behavior of the spin-orbit term in the nuclear shell model by analyzing relativistic and non-relativistic mean field calculations across nuclear sizes, revealing a strong correlation with nuclear radius.

Contribution

It provides a detailed analysis of the spin-orbit term's origin in nuclear mean fields, linking it to partial wave contributions, meson exchanges, and relativistic effects.

Findings

Strong correlation between spin-orbit strength and nuclear radius

Partial wave and meson contributions influence the spin-orbit term

Relativistic effects enhance the small component of Dirac spinors

Abstract

Quasi-nuclear systems, representing nuclei with variable size, are studied to investigate the occurrence of the spin-orbit term in the nuclear mean field in the transition from infinite nuclear matter to finite nuclei. Relativistic as well as non-relativistic mean field calculations based on models for the nucleon-nucleon ($NN$) interaction, which fit the $NN$ scattering data, are considered. A very strong correlation between the strength of the spin-orbit term and radius of the nuclear system is observed. The origin of the spin-orbit term is analyzed by inspecting the contributions of the different partial waves and various mesons in a One-Boson-Exchange model of the $NN$ interaction. The influence of correlation effects and the enhancement of the small component of Dirac spinors for nucleons in the nuclear medium is discussed.