Dynamics of nuclear single-particle structure in covariant theory of particle-vibration coupling: From light to superheavy nuclei

Abstract

The impact of particle-vibration coupling and polarization effects due to deformation and timeodd mean fields on single-particle spectra is studied systematically in doubly magic nuclei from low mass 56 Ni up to superheavy ones. Particle-vibration coupling is treated fully self-consistently within the framework of relativistic particle-vibration coupling model. Polarization effects due to deformation and time-odd mean field induced by odd particle are computed within covariant density functional theory. It has been found that among these contributions the coupling to vibrations makes a major impact on the single-particle structure. The impact of particle-vibration coupling and polarization effects on calculated single-particle spectra, the size of the shell gaps, the spin-orbit splittings and the energy splittings in pseudospin doublets is discussed in detail; these physical observables are compared with experiment. Particle-vibration coupling has to be taken into account when model calculations are compared with experiment since this coupling is responsible for observed fragmentation of experimental levels; experimental spectroscopic factors are reasonably well described in model calculations.

Impact of collective vibrations on quasiparticle states of open-shell odd-mass nuclei and possible interference with the tensor force

“…In the relativistic framework this was verified in the systematic studies of single-particle spectra of nuclei neighbouring to 56 Ni, 132 Sn and 208 Pb in Ref. [17] (see Ref. [18] and references therein for non-relativistic results).…”

“…The proper way to proceed is to take into account particle-vibration coupling (PVC) which affects both the wavefunctions and the energies of the states of odd spherical nuclei [16,17]. However, this has never been done in the context of the study of the effective tensor force because such investigation involves open-shell nuclei in which the pairing correlations of the superfluid type have to be taken into account.…”

“…In addition, Ref. [17] showed for the first time that PVC has an appreciable impact on the energy splittings of the spin-orbit and pseudospin doublets. For example, PVC decreases the splitting of the 1f 7/2 − 1f 5/2 spin-orbit doublet of 56 Ni by approximately 1.5 MeV.…”

Neutron drip line: Single-particle degrees of freedom and pairing properties as sources of theoretical uncertainties

“…This probably cannot be achieved just by fitting theoretical single-particle energies to experimental data because many of the experimental single-particle states are strongly fragmented by particle-vibrational coupling, in particular in spherical nuclei [7,42]. Therefore, the inclusion of the single-particle information into the fitting protocols of CEDF's is at the moment at its infancy [48,51].…”

“…Many physical observables related to the ground state properties (binding energies, charge radii, deformations, neutron skin thicknesses, the positions of drip lines etc [3]) and the properties of excited states (moments of inertia [11], the energies of (predominantly) single-particle states [7,42,45], fission barriers [46,47] etc) have been studied either globally or at least systematically in a specific region of the nuclear chart. Theoretical uncertainties for many physical observables have been defined.…”