Description of continuum structures in a discrete basis: Three-body  resonances and two-nucleon decays

Casal, J.; Rodríguez‐Gallardo, M.; Arias, J. M.; Gómez‐Camacho, J.; Fortunato, L.; Vitturi, A.

doi:10.21468/scipostphysproc.3.036

“…The experimental discovery of the radioactive decay of the nucleus 45 Fe [1] triggered the study of the physics of two-proton decay almost two decades ago. Similarly, 26 O [2] ignited the study of the exotic two-neutron radioactive decay, and attracted much attention in the last few years from both, theoretical and experimental side [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays, it is accepted that the drip line of the Oxygen chain occurs at 24 O [7] since the nuclei 25 O [8] and 26 O [3,4,9] are unbound. Experimentally, it has been established that the energy and half-life of 26 O are 18 ± 4 keV [6] and 4.5 ± 3 ps [5], respectively. Even if better statistics would be desired, these resonant parameters can be considered reliable.…”

Section: Introductionmentioning

confidence: 99%

“…Other theoretical approaches were also used to describe this nucleus. Green function formalism [10,20,21], continuum-coupled shell model in a spherical well [22], three-body model in the hyperspherical harmonics formalism [11], Gamow Shell Model [23], ab-initio Gamow Shell Model [24], core plus two valence particles selfconsistent model [25], and pseudostate method [26]. This paper intends to address some missing ingredients in the above references, in particular, the evolution of the resonances in the complex energy plane.…”

Section: Introductionmentioning

confidence: 99%

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

Affranchino,

Betan

2020

Preprint

0

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Background: 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.Purpose: 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.Method: 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.Results: 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.Conclusions: 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.

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“…The experimental discovery of the radioactive decay of the nucleus 45 Fe [1] triggered the study of the physics of two-proton decay almost two decades ago. Similarly, 26 O [2] ignited the study of the exotic two-neutron radioactive decay, and attracted much attention in the last few years from both, theoretical and experimental side [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…

Background: 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.

…”

mentioning

confidence: 99%

Neutron-pair structure in the continuum spectrum of O26

Affranchino

¹

,

Betán

²

2020

Phys. Rev. C

0

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Background: 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.Purpose: 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.Method: 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.Results: 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.Conclusions: 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.

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