3 research outputs found

    No-core shell model for 48-Ca, 48-Sc and 48-Ti

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    We report the first no-core shell model results for 48Ca^{48}Ca, 48Sc^{48}Sc and 48Ti^{48}Ti with derived and modified two-body Hamiltonians. We use an oscillator basis with a limited Ω\hbar\Omega range around 45/A1/325/A2/3=10.5MeV45/A^{1/3}-25/A^{2/3} = 10.5 MeV and a limited model space up to 1Ω1\hbar\Omega. No single-particle energies are used. We find that the charge dependence of the bulk binding energy of eight A=48 nuclei is reasonably described with an effective Hamiltonian derived from the CD-Bonn interaction while there is an overall underbinding by about 0.4 MeV/nucleon. However, the resulting spectra exhibit deficiencies that are anticipated due to: (1) basis space limitations and/or the absence of effective many-body interactions; and, (2) the absence of genuine three-nucleon interactions. We then introduce additive isospin-dependent central terms plus a tensor force to our Hamiltonian and achieve accurate binding energies and reasonable spectra for all three nuclei. The resulting no-core shell model opens a path for applications to the double-beta (ββ\beta\beta) decay process.Comment: Revised content and added reference

    The beta-beta two neutrino decay in 48Ca

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    A schematic study of the ββ2ν\beta \beta 2\nu -decay of 48Ca^{48}Ca is made in a shell-model approach. The emphasis is especially put on the role of the spin-orbit potential in relation with the contribution of other terms in the strong interaction. This is discussed with a particular attention to the behavior of these ones under the SU(4) symmetry. Different methods in calculating the transition amplitude are also looked at with the aim to determine their reliability and, eventually, why they don't work. Further aspects relative to the failure of the Operator Expansion Method to reproduce the results of more elaborate calculations are examined.Comment: 24 pages, 5 figure
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