[en] 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 J^πT=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

[en] The ab initio no-core shell model (NCSM) is extended to include a realistic three-body interaction in calculations for p-shell nuclei. The NCSM formalism is reviewed and new features needed in calculations with three-body forces are discussed in detail. We present results of first applications to ^6,7Li, ⁶He, ^7,8,10Be, ^10,11,12B, ¹²N, and ^10,11,12,13C using the Argonne V8^' nucleon-nucleon (NN) potential and the Tucson-Melbourne TM^'(99) three-nucleon interaction (TNI). In addition to increasing the total binding energy, we observe a substantial sensitivity in the low-lying spectra to the presence of the realistic three-body force and an overall improvement in level ordering and level spacing in comparison to experiment. The greatest sensitivity occurs for states where the spin-orbit interaction strength is known to play a role. In particular, with the TNI we obtain the correct ground-state spin for ^10,11,12B and ¹²N, contrary to calculations with NN potentials only

[en] The development of nuclear shapes under the extreme conditions of high angular momentum and/or temperature is examined. Scaling properties are used to demonstrate universal properties of both thermal expectation values of nuclear shapes as well as the minima of the free energy, which can be used to understand the Jacobi transition. A universal correlation between the width of the giant-dipole resonance and quadrupole deformation is found, providing a novel probe to measure the nuclear deformation in hot nuclei

[en] There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) can predict low-lying levels in p-shell nuclei. It is a challenging task to extend ab initio methods to describe nuclear reactions. In this contribution, we present a brief overview of the NCSM with examples of recent applications as well as the first steps taken toward nuclear reaction applications. In particular, we discuss cross section calculations of p+6Li and 6He+p scattering as well as a calculation of the astrophysically important 7Be(p,γ)8B S-factor

[en] We discuss the motivation, theory, and formulation of the ab initio No-Core Shell Model (NCSM). In this method the effective Hamiltonians are derived microscopically from realistic nucleon-nucleon (NN) and theoretical three-nucleon (NNN)potentials, as a function of the finite harmonic-oscillator (HO) basis space. We present converged results for the A = 3 and 4 nucleon systems, which are in agreement with results obtained by other exact methods, followed by results for p-shell nuclei. Binding energies, rms radii, excitation spectra, and electromagnetic properties are discussed. The favorable comparison with available data is a consequence of the underlying NN and NNN interactions rather than a phenomenological fit