Exploring quark mass dependent three-nucleon forces in medium-mass nuclei

TL;DR

This study examines the influence of a new quark mass dependent three-nucleon force, characterized by the coupling F2, on medium-mass nuclei using ab initio methods, revealing significant impacts on energies and radii but no systematic improvement in predictions.

Contribution

It introduces and assesses the impact of the dominant F2 three-nucleon interaction term within chiral effective field theory for medium-mass nuclei.

Findings

F2 interaction significantly affects energies and radii.

Short-range couplings are primarily responsible for the impact.

Including F2 does not systematically improve nuclear property predictions.

Abstract

Recently, new quark mass dependent three-nucleon (3N) forces have been identified, whose contributions in nuclear matter exceed expectations of Weinberg power-counting arguments. In this work, we investigate the impact of the most dominant new interaction term, characterized by the coupling $F_2$, in ab initio calculations of medium-mass nuclei. For this, we combine the new $F_2$ interaction with established 3N interactions up to next-to-next-to-leading order (N$^2$LO) and next-to-next-to-next-to-leading order (N$^3$LO) in chiral effective field theory. We explore two fit strategies for the low-energy couplings. The first is based only on few-body observables, while the second also incorporates information from $^{16}$O. Generally, we find that the $F_2$ interaction has a significant impact on energies and radii, however mainly due to changes in the short-range couplings. Overall, we do not find systematic improvements in the reproduction of medium-mass nuclei when the additional $F_2$ interaction is included.