Generic features of the neutron-proton interaction

TL;DR

This paper demonstrates that fully aligned neutron-proton pairs are fundamental in low-energy nuclear spectroscopy across various nuclei, driven by angular momentum coupling and intrinsic interaction properties.

Contribution

It analytically reveals the generic dominance of aligned neutron-proton pairs in nuclei with valence nucleons in high-j orbitals, extending across different nuclear configurations.

Findings

Fully aligned neutron-proton pairs dominate low-energy spectra.

Analytical demonstration across multiple nuclear systems.

Dominance results from angular momentum coupling and interaction properties.

Abstract

We show that fully aligned neutron-proton pairs play a crucial role in the low-energy spectroscopy of nuclei. with valence nucleons in a high-j orbital. Their dominance is valid in nuclei with valence neutrons and protons in different high-j orbitals as well as in N = Z nuclei, where all nucleons occupy the same orbital. We demonstrate analytically this generic feature of the neutron-proton interaction for a variety of systems with four valence nucleons interacting through realistic, effective forces. The dominance of fully aligned neutron-proton pairs results from the combined effect of (i) angular momentum coupling and (ii) basic properties of the neutron-proton interaction.