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Energies of the ground state and first excited 0+ state in an exactly solvable pairing model

  • N. Dinh Dang

Abstract:

Several approximations are tested by calculating the ground-state energy and the energy of the first excited 0+ state using an exactly solvable model with two symmetric levels interacting via a pairing force. They are the BCS approximation (BCS), Lipkin-Nogami (LN) method, random-phase approximation (RPA), quasiparticle RPA (QRPA), the renormalized RPA (RRPA), and renormalized QRPA (RQRPA). It is shown that, in the strong-coupling regime, the QRPA which neglects the scattering term of the model Hamiltonian offers the best fit to the exact solutions. A recipe is proposed using the RRPA and RQRPA in combination with the pairing gap given by the LN method. Applying this recipe, it is shown that the superfluid-normal phase transition is avoided, and a reasonably good description for both of the ground-state energy and the energy of the first excited 0+ state is achieved.

PACS. 21.60.Jz Hartree-Fock and random-phase approximations – 21.60.-n Nuclear-structure models and methods 

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Copyright information

© Società Italiana di Fisica and Springer-Verlag 2003

Authors and Affiliations

  • N. Dinh Dang
    • 1
  1. 1.RI-beam factory project office, RIKEN, 2-1 Hirosawa, Wako, 351-0198 Saitama, Japan and Institute for Nuclear Science and Technique, VAEC, Hanoi, VietnamJP

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