An optimized chiral nucleon-nucleon interaction at next-to-next-to-leading order

TL;DR

This paper presents an optimized chiral nucleon-nucleon interaction at next-to-next-to-leading order that accurately fits low-energy nuclear data and simplifies the understanding of nuclear structure without heavily relying on three-nucleon forces.

Contribution

It introduces a new optimized chiral NN interaction (NNLOopt) with improved fit quality and reduced three-nucleon force contributions, advancing nuclear modeling accuracy.

Findings

NNLOopt achieves   .1 per degree of freedom below 125 MeV.

Three-nucleon force contributions are smaller with NNLOopt compared to previous models.

Many nuclear properties can be explained without explicitly including three-nucleon forces.

Abstract

We optimize the nucleon-nucleon interaction from chiral effective field theory at next-to-next- to-leading order. The resulting new chiral force NNLOopt yields \chi^2 \approx 1 per degree of freedom for laboratory energies below approximately 125 MeV. In the A = 3, 4 nucleon systems, the contributions of three-nucleon forces are smaller than for previous parametrizations of chiral interactions. We use NNLOopt to study properties of key nuclei and neutron matter, and demonstrate that many aspects of nuclear structure can be understood in terms of this nucleon-nucleon interaction, without explicitly invoking three-nucleon forces.