Theoretical investigation of two-particle two-hole effects on spin-isospin excitations through charge-exchange reactions

荷電交換反応を用いたスピンアイソスピン励起に対する2粒子2空孔効果の理論研究

福井 徳朗*; 湊 太志   

Fukui, Tokuro*; Minato, Futoshi

The effect of the two-particle two-hole (2p2h) configuration on the Gamow-Teller (GT) transition causes the quenching problem of GT resonances. To solve this problem, we investigate the GT resonance of Ca(p,n)Sc. The Fermi transition of Ca is also investigated in order to demonstrate our framework. The transition density is calculated by the second Tamm-Dancoff approximation, whereas the distorted-wave Born approximation is employed to described the reaction process. A phenomenological Gaussian interaction is used to prepare the form factor. For the Fermi transition, our approach describes better the experimental behavior of the cross section than that calculated by the Lane model, which is conventionally adopted. We show the 2p2h effect on the GT transition decreases the magnitude of the cross section and does not change the shape of the angular distribution. The transition on the present reaction is found to play a negligible role.