Brueckner G-matrix approach for neutron-proton pairing correlations in the deformed BCS approach

초록

Ground states of even-even Ge isotopes with mass number A = 64-76 have been studied in the deformed Bardeen-Cooper-Schrieffer (BCS) theory by taking neutron-proton (np) pairing correlations as well as neutron-neutron (nn) and proton-proton (pp) pairing correlations. The np pairing has two different modes J = 0, T = 1 (isotriplet) and J = 1, T = 0 (isosinglet). In this work, the Brueckner G matrix, based on the CD-Bonn potential, has been exploited to reduce the ambiguity regarding nucleon-nucleon interactions inside nuclei compared to the results by a simple schematic phenomenological force. We found that the G matrix plays important roles to obtain reasonable descriptions of even-even nuclei compared to the schematic force. The np pairing strength has been shown to have a clear correlation with quadrupole deformation parameter beta(2) for the isotopes, and affects the smearing of the Fermi surfaces of not only N = Z nuclei but also N not equal Z nuclei. In particular, the coexistence of the like particle (nn and pp) and the np pairing modes was found to become more salient by the G-matrix approach than by the schematic force approach.

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