Tensor effective interaction in self-consistent Random Phase Approximation calculations

TL;DR

This paper investigates how adding a tensor-isospin term to finite-range Gogny interactions influences nuclear structure calculations, notably affecting single particle energies and, in some cases, bulk properties across various isotopes.

Contribution

It introduces a tensor-isospin term into Gogny-type forces and analyzes its impact on ground and excited states in multiple isotopes, highlighting effects on single particle energies and bulk properties.

Findings

Tensor force significantly alters nucleon single particle energies.

Some bulk nuclear properties are sensitive to the tensor interaction.

The tensor term improves the reproduction of specific excited state energies.

Abstract

We present a study of the effects of the tensor-isospin term of the effective interaction in Hartree-Fock and Random Phase Approximation calculations. We used finite-range forces of Gogny type, and we added to them a tensor-isospin term which behaves, at large internucleonic distances, as the analogous term of the microscopic interactions. The strength of this tensor force has been chosen to reproduce the experimental energy of the lowest 0$^-$ excited state in $^{16}$O, which shows large sensitivity to this term of the interaction. With these finite-range interactions, we have studied the effects of the tensor-isospin force in ground and excited states of carbon, oxygen, calcium, nickel, zirconium, tin and lead isotopes. Our results show that the tensor force affects mainly the nucleon single particle energies. However, we found some interesting cases where also bulk nuclear properties are sensitive to the tensor interaction.