Determination of Dipole Polarization Effects in 7Li and 11Li

The structure of 6Li, 7Li and 11Li nuclei is investigated in a model space which includes all configurations with oscillator energy up to 3hω above the ground state configuration. The energy spectra and electromagnetic properties of the low-lying states are determined with various two-body interactions, which are derived from the Bonn potential. In addition the calculation determines the dipole polarizability of7 Li and 11Li caused from virtual E1 excitations to the positive parity states of these nuclei.

Self-Consistent Green Function Method in Nuclear Matter

Symmetric nuclear matter is studied within the Brueckner-Hartree-Fock (BHF) approach and is extending to the self-consistent Green’s function (SCGF) approach. Both approximations are based on realistic nucleon-nucleon interaction; that is, CD-Bonn potential is chosen. The single-particle energy and the equation of state (EOS) are studied. The Fermi energy at the saturation point fulfills the Hugenholtz-Van Hove theorem. In comparison to the BHF approach, the binding energy is reduced and the EOS is stiffer. Both the SCGF and BHF approaches do not reproduce the correct saturation point. A simple contact interaction should be added to SCGF and BHF approaches to reproduce the empirical saturation point.

NUCLEON-DEUTERON SCATTERING WITH Δ-ISOBAR EXCITATION: NEW TECHNICAL DEVELOPMENTS

A new technique for solving three-particle scattering equations is developed. It is based on the two-dimensional Chebyshev expansion of the two-baryon transition matrix. Its validity and its effectiveness is demonstrated. Furthermore, a new perturbative technique for simulating exact scattering results is developed. It has the potential for understanding three-particle reaction mechanisms in detail. The dynamics of the examples is based on a two-baryon potential which allows for the excitation or a nucleon to a Δ-isobar; the coupled-channel potential yields an effective three-nucleon force in the three-nucleon system. The purely nucleonic reference potential is the charge-dependent Bonn potential.

CORRELATIONS AND THE RELATIVISTIC STRUCTURE OF THE NUCLEON SELF-ENERGY

A key point of Dirac-Brueckner-Hartree-Fock calculations for nuclear matter is to decompose the self-energy of the nucleons into Lorentz scalar and vector components. A new method is introduced for this decomposition. It is based on the dependence of the single-particle energy on the small components in the Dirac spinors used to calculate the matrix elements of the underlying NN interaction. The resulting Dirac components of the self-energy depend on the momentum of the nucleons. At densities around and below the nuclear matter saturation density this momentum dependence is dominated by the non-locality of the Brueckner G matrix. At higher densities these correlation effects are suppressed and the momentum dependence due to the Fock exchange terms is getting more important. Differences between symmetric nuclear matter and neutron matter are discussed. Various versions of the Bonn potential are considered.