Nuclear forces and nuclear excited states

TL;DR

This paper investigates how different components of the two-nucleon interaction influence the excited states of sd-shell nuclei using the nuclear shell model, highlighting the dominant role of the central force and the importance of Hamiltonian projection.

Contribution

It introduces a detailed analysis of the individual contributions of central, spin-force, and tensor forces in nuclear excited states within the shell model framework.

Findings

Central force mainly influences excitation energy.

Spin-orbit and tensor forces are crucial in specific cases like $^{22}$O.

Hamiltonian projection approach effectively assesses force contributions.

Abstract

In this work, the role of the central, spin-force and tensor forces of two-nucleon interaction in building the first 2$^+$ and 4$^+$ states of 20 sd-shell nuclei is studied. Calculations are performed within the framework of the nuclear shell model. It is shown that the central force predominantly contributes to the excitation energy. While the spin-orbit and tensor forces contribute relatively less, their roles are noted crucial in a few cases, such as in $^{22}$O. Further, it is demonstrated that the Hamiltonian projection approach should be preferred for rightly assessing the contributions of each force to the excitation energy.