Shell effects in nuclei with vector self-coupling of theωmeson in the relativistic Hartree-Bogoliubov theory

Abstract

Shell effects in nuclei about the stability line are investigated within the framework of the relativistic Hartree-Bogoliubov (RHB) theory with self-consistent finite-range pairing. Using two-neutron separation energies of Ni and Sn isotopes, the role of $\ensuremath{\sigma}\ensuremath{-}$ and $\ensuremath{\omega}$-meson couplings on the shell effects in nuclei is examined. It is observed that the existing successful nuclear forces (Lagrangian parameter sets) based upon the nonlinear scalar coupling of the $\ensuremath{\sigma}$ meson exhibit shell effects which are stronger than suggested by the experimental data. We have introduced nonlinear vector self-coupling of the $\ensuremath{\omega}$ meson in the RHB theory. It is shown that the inclusion of the vector self-coupling of the $\ensuremath{\omega}$ meson in addition to the nonlinear scalar coupling of the $\ensuremath{\sigma}$ meson provides a good agreement with the experimental data on shell effects in nuclei about the stability line. A comparison of the shell effects in the RHB theory is made with the Hartree-Fock-Bogoliubov approach using the Skyrme force SkP. It is shown that the oft-discussed shell quenching with SkP is not consistent with the available experimental data.