Relativistic Hartree-Bogoliubov theory: static and dynamic aspects of exotic nuclear structure

We present a review of recent applications of self-consistent relativistic mean-field models to exotic nuclear structure. Based on concepts of non-renormalizable effective relativistic field theories and density functional theory, these models provide a rich theoretical framework for studies of nuclei along the valley of beta-stability, exotic nuclei with extreme ground-state isospin values and close to the particle drip lines. A quantitative microscopic description of ground states and properties of excited states in nuclei far from stability necessitates a unified description of mean-field and pairing correlations. The relativistic Hartree-Bogoliubov (RHB) model has been employed in studies of structure phenomena that include: the description of the neutron drip line in light nuclei and the microscopic mechanism for the formation of neutron halos; the reduction of the effective spin-orbit interaction and the resulting modification of surface properties in drip line nuclei; the suppression of shell effects and the onset of deformation and shape coexistence in neutron-rich nuclei; nuclei at the proton drip-line and ground-state proton emitters in the region of deformed rare-earth nuclei; shape coexistence phenomena in neutron-deficient nuclei. The cranked RHB framework has been used for the description of rotational excitations: superdeformed and highly deformed rotational bands in the mass A similar to 60 region, rotational bands built on superdeformed minima in the A similar to 140-150 and the A similar to 190 mass regions, and on normal deformed minima in the rare-earth region, smooth termination of rotational bands, rotational and quasiparticle properties of the heaviest actinide nuclei. The relativistic random phase approximation (RRPA) has been employed in studies of nuclear compression modes, nuclear matter asymmetry energy, multipole giant resonances and low-lying collective states in spherical nuclei, the evolution of the low-lying isovector dipole response in nuclei with a large neutron excess, pygmy resonances, isoscalar dipole and toroidal dipole resonances. The relativistic quasiparticle RPA, formulated in the canonical single-nucleon basis of the RHB, has been applied in the description of the low-energy multipole response of unstable weakly bound nuclei. The self-consistent relativistic mean-field framework has been extended to include density-dependent meson-nucleon vertex functions. Compared with standard relativistic effective interactions with non-linear meson-exchange terms, the density-dependent meson-nucleon couplings provide an improved description of asymmetric nuclear matter, neutron matter and nuclei far from stability. Effective density-dependent interactions have also been used in relativistic (Q)RPA calculations of giant resonances, and in a microscopic analysis of the nuclear matter compressibility and symmetry energy. (c) 2004 Elsevier B.V. All rights reserved.