Recent developments in no-core shell-model calculations

TL;DR

The paper reviews recent progress in the no-core shell model (NCSM), an ab initio method for light nuclei, highlighting developments in effective interactions, extensions to heavier nuclei, and future directions including continuum coupling.

Contribution

It provides a comprehensive overview of recent advancements in NCSM, including new effective interaction techniques and extensions to nuclear reactions and continuum states.

Findings

Successful application of chiral two- and three-nucleon interactions.

Extensions to heavier nuclei using importance truncation.

Development of NCSM with continuum for open systems.

Abstract

We present an overview of recent results and developments of the no-core shell model (NCSM), an ab initio approach to the nuclear many-body problem for light nuclei. In this approach, we start from realistic two-nucleon or two- plus three-nucleon interactions. Many-body calculations are performed using a finite harmonic-oscillator (HO) basis. To facilitate convergence for realistic inter-nucleon interactions that generate strong short-range correlations, we derive effective interactions by unitary transformations that are tailored to the HO basis truncation. For soft realistic interactions this might not be necessary. If that is the case, the NCSM calculations are variational. In either case, the ab initio NCSM preserves translational invariance of the nuclear many-body problem. In this review, we, in particular, highlight results obtained with the chiral two- plus three-nucleon interactions. We discuss efforts to extend the applicability of the NCSM to heavier nuclei and larger model spaces using importance-truncation schemes and/or use of effective interactions with a core. We outline an extension of the ab initio NCSM to the description of nuclear reactions by the resonating group method technique. A future direction of the approach, the ab initio NCSM with continuum, which will provide a complete description of nuclei as open systems with coupling of bound and continuum states, is given in the concluding part of the review.