Abstract
The occurrence of low-lying charge-exchange non-spin-flip dipole modes below the giant resonance in neutron-rich nuclei is predicted on the basis of nuclear density functional theory. The ground and excited states are described within the framework of the self-consistent Hartree–Fock–Bogoliubov theory and the proton-neutron quasiparticle-random-phase approximation employing a Skyrme-type energy density functional. The model calculations are performed for the spherical neutron-rich Ca, Ni, and Sn isotopes. It is found that the low-lying states appear sensitive to the shell structure associated with the excitation below the Gamow–Teller states. Furthermore, the pygmy resonance emerges below the giant resonance when the neutrons occupy the low- orbitals analogous to the pygmy resonance seen in the electric-dipole response.
- Received 18 August 2017
DOI:https://doi.org/10.1103/PhysRevC.96.051302
©2017 American Physical Society