Large-basis shell model studies of light nuclei with a multivalued G-matrix effective interaction

Ab initio shell model calculations with three-body effective interactions for p-shell nuclei

We present a qualitative improvement of the ab initio no-core shell model (NCSM) approach by implementing three-body interaction capability for p-shell nuclei. We report the first calculations using three-body effective interactions derived from realistic nucleon-nucleon potentials for 6Li, 8Be, and 10B and demonstrate that the use of three-body effective interactions speeds up the convergence of the NCSM approach. For 10B, we predict JpiT = 1(+)0 ground state, contrary to the experimental observation of 3(+)0, when the AV8(') potential is used, indicating the need for true three-body forces.

Six-nucleon spectroscopy from a realistic nonlocal Hamiltonian

We apply the ab initio no-core nuclear shell model to solve the six-nucleon systems, (6)Li and (6)He, interacting by realistic nucleon-nucleon ( NN) potentials. In particular, we present the first results for A = 6 with the nonlocal CD-Bonn NN potential. The resulting (6)Li binding energy -29.3(6) MeV and the excitation spectra improve the agreement between the theory and experiment compared to results with local NN potentials, but the need for the inclusion of a real three-body interaction and/or further improvement of the NN forces remains. We predict properties of the (6)He dipole modes, a subject of current controversy.

Properties of 12C in the Ab initio nuclear shell model

We obtain properties of 12C in the ab initio no-core nuclear shell model. The effective Hamiltonians are derived microscopically from the realistic CD Bonn and the Argonne V8' nucleon-nucleon (NN) potentials as a function of the finite harmonic oscillator basis space. Binding energies, excitation spectra, and electromagnetic properties are presented for model spaces up to 5Planck's over 2piOmega. The favorable comparison with available data is a consequence of the underlying NN interaction rather than a phenomenological fit.

Morphing the shell model into an effective theory

We describe a strategy for attacking the canonical nuclear structure problem-bound-state properties of a system of point nucleons interacting via a two-body potential-which involves an expansion in the number of particles scattering at high momenta, but is otherwise exact. The required self-consistent solutions of the Bloch-Horowitz equation for effective interactions and operators are obtained by an efficient Green's function method based on the Lanczos algorithm. We carry out this program for the simplest nuclei, d and 3He, in order to explore the consequences of reformulating the shell model as a controlled effective theory.