NNcorrelations and relativistic Hartree-Fock in finite nuclei

Abstract

Two different approximation schemes for the self-consistent solution of the relativistic Brueckner-Hartree-Fock equation for finite nuclei are discussed using realistic One-Boson-Exchange potentials. In a first scheme, the effects of correlations are deduced from a study of nuclear matter and parameterized in terms of an effective σ, ω and π exchange. Employing this effective interaction relativistic Hartree-Fock equations are solved for finite nuclei 16 O, 40 Ca and 48 Ca. In the second approach the effect of correlations are treated in the BruecknerHartree-Fock approximation directly for the finite nuclei, but the modifications of the Dirac spinors in the medium are derived from nuclear matter assuming a local-density approximation. Both approaches yield rather similar results for binding energies and radii in fair agreement with experimental data. The importance of the density dependent correlation effects is demonstrated and different ingredients to the spin-orbit splitting in the shell-model of the nucleus are discussed.

Collective excitations and ground state correlations

“…The correlations increase the value for the calculated binding energy and lead to an enhancement for the calculated radius. Therefore correlations of the SRPA type combined with the features of the Dirac-BHF approximation [18] may produce results for the ground-state properties of finite nuclei, which are in good agreement with the experimental data.…”

“…The relativistic features tend to significantly improve the agreement between calculated values for the energies and radii and the corresponding experimental data [18,19]. The remaining discrepancies (around 0.7 MeV per nucleon in energy and around 0.2 fm for the radius of light nuclei like 16 O and 40 Ca), however, are still too large to be accounted for.…”

Recent Progress in Quantum Hadrodynamics

“…Relativistic HF calculations that include charged mesons and that examine the relation of the scalar and vector self-energies to DBHF calculations in nuclear matter are carried out in [Bo87,Ce92,Be93,Fr93a,Bo94a,Fr94a,Ma94c,Zh94a,Be96]. The existence of large Lorentz scalar and vector self-energies appears to be a firm conclusion.…”

Dirac effects in the Hartree-Fock description of finite nuclei employing realistic forces

“…We tried to remove this sensitivity by inspection of nuclear matter at low densities. The Dirac-Hartree, as well as the Dirac-Hartree-Fock equation discussed below, were solved by a matrix diagonalisation method, expanding the wavefunctions in a basis of states for a spherical cavity [20]. The new computer code has been tested by comparing the results with those presented by Bouyssy et al [21].…”