The ab initio No-Core Shell Model and Light Nuclei

Abstract

The ab initio no-core shell model (NCSM) is a well-established theoretical framework aimed at an exact description of nuclear structure starting from high-precision interactions between the nucleons. In the NCSM we consider a system of A point-like, non-relativistic nucleons that interact by realistic inter-nucleon interactions. We consider two-nucleon interactions that reproduce nucleon-nucleon phase shifts with high precision, typically up to 350 MeV lab energy. We can also include three-nucleon interactions with terms, e.g., related to two-pion exchanges with an intermediate delta excitation. Both semi-phenomenological potentials, based on meson-exchange models, as well as modern chiral interactions can be considered. The performance of the NCSM within nuclear physics will be exemplified by showing results from studies of light nuclei. Major challenges in the future development of the method will be outlined.

Structure of C9 through proton resonance scattering with the Texas Active Target detector

“…Enormous progress has been achieved over the past two decades in describing the properties of light nuclei starting from interacting nucleons and using realistic twonucleon and three-nucleon forces or chiral interactions. Sophisticated methods, such as Quantum Monte Carlo approach [1], No Core Shell Model [2], No Core Configuration Interaction [3], coupled-cluster theory [4] have been developed to make robust predictions of groundstate energies [5], level structure [1], spectroscopic factors and partial widths [6], scattering phase shifts [7], electromagnetic moments and transitions [8] in light nuclei. Reliable experimental benchmarks are necessary to facilitate further theoretical progress.…”

Living on the edge of stability, the limits of the nuclear landscape

“…Benchmarking of calculations with chiral NN+3NF interactions using NCSM[160] and Hyperspherical Harmonics[161] methods. (From Refs [39,162]…”

“…Electric quadrupole moments, magnetic dipole moments, and charge radii of Li isotopes obtained in NCSM and compared with experiment. (From Refs [162,173]…”

“…Theoretical results include the 4 He g.s., 0 + 0, 0 − 0, 1 − 0, 1 − 1, 2 − 0, and 2 − 1 states. (From Refs [146,162]…”

Unitary scheme model calculations of the ground and excited state characteristics of 3H and 4He

“…Barrett, Navrátil, and Vary [18] discussed, in detail, the extension of the ab initio NCSM to nuclear reactions and outlined some of the promising future directions for research emerging from the foundation provided by the NCSM, including a microscopic non-perturbative framework for a theory with a core. In the NCSM, Forssén, Navrátil and Quaglioni [19] considered a system of point-like non-relativistic nucleons that interact through realistic inter-nucleon interactions. They considered two-nucleon interactions that reproduce nucleon-nucleon phase shifts with high precision, typically up to 350 MeV in lap energy.…”