| 1. |
- Dussel, G. G., et al.
(författare)
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Collective excitations in the continuum
- 2009
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:6, s. 064311-
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Tidskriftsartikel (refereegranskat)abstract
- Pairing (particle-particle) giant resonances are analyzed within a shell-model formalism in the complex energy plane with the aim of understanding why they have not been observed so far. A comparison is made with the equivalent particle-hole mode by applying the formalism to the analysis of the well-understood particle-hole giant resonance. It is found that because of the proper treatment of the continuum intrinsic to the formalism, giant pairing resonances lie much higher than previously predicted and that some of them may be too wide to be observed, whereas others are meaningful excitations. For these, new experimental searches are proposed.
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| 2. |
- Dussel, G. G., et al.
(författare)
-
One- and two-quasiparticle states in the complex energy plane
- 2007
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 789, s. 182-200
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Tidskriftsartikel (refereegranskat)abstract
- One- and two-quasi particle states are studied in the complex energy plane. It is found that the pairing interaction does not change the character of the complex state. If a normal state is a physically meaningful resonance, then it will remain as such throughout the shell and if it is unphysical it will also remain as such throughout the shell. An important consequence of this is that it justifies the use of bound representations to evaluate many-body systems within the shell-model in cases where the single-particle states are narrow resonances. The character of two-quasiparticle states may oscillate between meaningful resonances and unphysical complex excitations as the number of particles increases.
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| 3. |
- Id Betan, Rodolfo M, et al.
(författare)
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Complex shell model representation including antibound states
- 2005
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 72:5, s. 054322-
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Tidskriftsartikel (refereegranskat)abstract
- A generalization of the complex shell model formalism is presented that includes antibound states in the basis. These states, together with bound states, Gamow states, and the continuum background, represented by properly chosen scattering waves, form a representation in which all states are treated on the same footing. Two-particle states are evaluated within this formalism, and observable two-particle resonances are defined. The formalism is illustrated in the well-known case of Li-11 in its bound ground state and in Ca-70(g.s.), which is also bound. Both cases are found to have a halo structure. These halo structures are described within the generalized complex shell model. We investigated the formation of two-particle resonances in these nuclei, but no evidence of such resonances was found.
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