Deformation or spherical symmetry in 10Be and the inversion of 1/2- - 1/2+ states in 11Be

TL;DR

This paper investigates the energy states of 11Be using core deformation and spherical symmetry assumptions, demonstrating that different theoretical approaches yield similar results under certain conditions.

Contribution

It compares deformation-based and spherical symmetry models for 11Be, showing their equivalence when phonon energy is neglected.

Findings

Deformation and spherical models produce similar energy results for 11Be.

Neglecting phonon energy simplifies the equivalence of models.

The approach clarifies the inversion of 1/2- and 1/2+ states in 11Be.

Abstract

For a core plus one neutron system like 11Be we have calculated the energies of the 1/2- and 1/2+ states assuming a deformation of the core deduced from the low energy 2+ state properties or taking into account the coupling of the neutron with this 2+ state interpreted as a spherical one-phonon state. We have shown that the two derivations yield identical results if the phonon energy is neglected in the second derivation and close results in the general case.