Landscape of pear-shaped even-even nuclei
Yuchen Cao🇺🇸 · Sylvester E. Agbemava🇺🇸 · Anatoli V. Afanasjev🇺🇸 · Witold Nazarewicz🇺🇸 · Erik Olsen🇧🇪
The phenomenon of reflection-asymmetric nuclear shapes is relevant to nuclear stability, nuclear spectroscopy, nuclear decays and fission, and the search for new physics beyond the standard model. Global surveys of ground-state octupole deformation, performed with a limited number of models, suggest that the number of pear-shaped isotopes is fairly limited across the nuclear landscape. We carry out global analysis of ground-state octupole deformations for particle-bound even-even nuclei with and using nuclear density functional theory (DFT) with several non-relativistic and covariant energy density functionals. In this way, we can identify the best candidates for reflection-asymmetric shapes. The calculations are performed in the frameworks of axial reflection-asymmetric Hartree-Fock-Bogoliubov theory and relativistic Hartree-Bogoliubov theory using DFT solvers employing harmonic oscillator basis expansion. We consider five Skyrme and four covariant energy density functionals. We predict several regions of ground-state octupole deformation. In addition to the "traditional" regions of neutron-deficient actinide nuclei around Ra and neutron-rich lanthanides around Ba, we identified vast regions of reflecion-asymmetric shapes in very neutron-rich nuclei around Gd and Pu, as well as in several nuclei around Ba. Our analysis suggests several promising candidates with stable ground-state octupole deformation, primarily in the neutron-deficient actinide region, that can be reached experimentally. Detailed comparison between Skyrme and covariant models is performed.