Exploration of the exotic structure in Ce isotopes by the relativistic point-coupling model combined with complex momentum representation

The relativistic point-coupling model is combined with the complex momentum representation with resonances considered by BCS approximation, which is called the RMFPC-CMR-BCS theory. The RMFPC-CMR-BCS theory can be used to explore exotic structures in nuclei. The resonant levels near the continuum threshold can be shown to play an important role in the formation of exotic phenomena. The Ce isotopes are taken as examples, and the energy and width are obtained for the bound states and resonant states in a clear shell structure. The occupation probabilities of valence nucleons in these orbits close to the Fermi surface are calculated, and the contributions of every orbit to the nuclear density distribution are compared. It is found that several resonant levels with low-angular momentum contribute fairly diffuse density distributions, which result in the appearance of halos and giant halos in the Ce isotopes close to the neutron drip line. Ce186-190 are suggested to be halo nuclei and Ce192-198 are suggested to be giant halo nuclei, which agrees the relativistic HFB calculations and is expected to be verified in experiment.