Neutron-pair structure in the continuum spectrum of ${}^{26}$O

Abstract

The structure of ${}^{26}$O is currently being investigated on both theoretical and experimental fronts. It is well established that it is unbound and the resonance parameters are fairly well-known. The theoretical analysis may involved two- and three-body interactions, as well as correlations with the continuum spectrum of energy. In order to properly assess the structure of the ground and excited states, it is imperative to include a large single particle representation with the right asymptotic behavior. The purpose of this work is to provide details of the single particle continuum configurations of the ground and excited $0^{+}$ states. We use a large complex energy single particle basis, formed by resonances and complex energy scattering states, the so called Berggren basis, and a separable interaction, which is convenient to solve in a large model space. Three $0^{+}$ states were found in the complex energy plane. Changes of the resonant parameters, i.e. energy and width, were analyzed as a function of strength of the residual interaction. It is shown how a subtle difference in the interaction could change the unbound character of ${}^{26}$O into a Borromean nucleus. Only one of the two excited states can be considered as a candidate for a physical meaningful resonance. The calculated occupation probabilities are in agreement with other theoretical approaches although the calculated half live is three-order of magnitude smaller than the experimental one.

arXiv comment7 pages, 5 figures, 5 tables, 47 references

References in corpus (23)

• Three-body forces and the limit of oxygen isotopes
• Gamow Shell Model Description of Neutron-Rich Nuclei
• Shell Model in the Complex Energy Plane
• Two-Particle Resonant States in a Many-Body Mean Field
• Discrete and continuum spectra in the unified shell model approach
• Continuum Shell Model
• Evidence for the ground-state resonance of 26O
• Beyond the Neutron Drip-Line: The Unbound Oxygen Isotopes 25O and 26O
• Study of two-neutron radioactivity in the decay of 26O
• Quantified Gamow Shell Model interaction for $psd$-shell nuclei
• Mean-field approach to nuclear structure with semi-realistic nucleon-nucleon interactions
• Shell model in the complex energy plane and two-particle resonances
• Continuum effects in neutron-drip-line oxygen isotopes
• Correlated two-neutron emission in the decay of unbound nucleus 26O
• Lifetime and fragment correlations for the two-neutron decay of ${}^{26}$O ground state
• Nuclear Halos and Drip Lines in Symmetry-Conserving Continuum HFB Theory
• Generalized Faddeev equations in the AGS form for deuteron stripping with explicit inclusion of target excitations and Coulomb interaction
• An {\it ab-initio} Gamow shell model approach with a core
• Decay dynamics of the unbound ${}^{25}$O and ${}^{26}$O nuclei
• On the mean value of the energy for resonant states
• Three-body model calculation of the 2${}^{+}$ state in ${}^{26}$O
• A combined mean-field and three-body model tested on the ${}^{26}$O-nucleus
• Description of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays