Competition of deformation and neutron– proton pairing in Gamow–Teller transitions for 56,58Ni and 62,64Ni

Abstract

We investigate effects of unlike-pairing correlations by neutron-proton (np) pairs on Gamow-Teller strength distributions for even-even Ni isotopes, 56,58,60,62,64Ni, by taking into account nuclear deformation in a deformed Woods-Saxon mean field. Our calculations based on a deformed Bardeen- Cooper-Schriffer approach which preserves the axial and the time-reversal symmetry are performed within a deformed quasiparticle random phase approximation, in which we explicitly include the deformation and the unlike-pairing as well as the like-pairing correlations by neutron-neutron and proton- proton pairs. Competition of these two effects, the deformation and the pairing correlations, is shown to be able to affect more or less the GT strength distributions of the even-even Ni isotopes.