Ab initio shell model with a genuine three-nucleon force for the p-shell nuclei

TL;DR

This paper extends the ab initio no-core shell model to include realistic three-nucleon forces, improving predictions of binding energies and spectra for p-shell nuclei, and achieving better agreement with experimental data.

Contribution

The study introduces a formalism incorporating three-nucleon interactions into the NCSM and demonstrates its effectiveness on various p-shell nuclei, showing significant improvements over previous models.

Findings

Enhanced binding energy predictions.

Improved level-ordering and spacing in spectra.

Correct ground-state spins for certain nuclei.

Abstract

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 the 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.