Effects of deformation and neutron-proton pairing on the Gamow-Teller transitions forMg24,26in a deformed quasiparticle random-phase approximation

Abstract

We investigate effects of neutron-proton ($np$) pairing correlations on the Gamow-Teller (GT) transition of $^{24,26}\mathrm{Mg}$ by explicitly taking into account deformation effects. Our calculation is performed by a deformed quasiparticle random phase approximation (DQRPA) which includes the deformation at the Bardeen-Cooper-Schrieffer and RPA stage. In this paper, we include the $np$ pairing as well as neutron-neutron ($nn$) and proton-proton ($pp$) paring correlations to the DQRPA. Our new formalism is applied to the GT transition of well-known deformed Mg isotopes. The $np$ pairing effect is found to affect more or less the GT distribution of $^{24}\mathrm{Mg}$ and $^{26}\mathrm{Mg}$. But the deformation effect turns out to be much larger than the $np$ paring effect because the Fermi surfaces smear more widely by the deformation rather than the $np$ pairing correlations. Correlations between the deformation and the $np$ pairing effects and their ambiguities are also discussed with the comparison to experimental GT strength data by triton and $^{3}\mathrm{He}$ beams.