Radii of light nuclei from the Jacobi No-Core Shell Model

Abstract

Accurately determining the size of the atomic nucleus with realistic nuclear forces is a long outstanding issue of nuclear physics. The no-core shell model (NCSM), one of the powerful ab initio methods for nuclear structure, can achieve accurate energies of light nuclei. The extraction of converged radii is more difficult. In this work, we present a novel method to effectively extract the radius of light nuclei by restoring the long-range behavior of densities from NCSM calculations. The correct large distance asymptotic of two-body relative densities are deduced based on the NCSM densities in limited basis size. The resulting radii using the corrected densities show a nice convergence. The root-mean-square matter and charge radii of $^{4,6,8}$He and $^{6,7,8}$Li can be accurately obtained based on Jacobi-NCSM calculations with the high-precision chiral two-nucleon and three-nucleon forces combined with this new method. Our method can be straightforwardly extended to other ab initio calculations, potentially providing a better description of nuclear sizes with realistic nuclear forces.