Chiral three-nucleon force and continuum for dripline nuclei and beyond

TL;DR

This paper develops a theoretical framework combining chiral three-nucleon forces with continuum effects using the Gamow shell model, to accurately describe dripline nuclei like neutron-rich oxygen isotopes.

Contribution

It introduces a novel approach to incorporate chiral three-nucleon forces within the continuum Berggren representation in the Gamow shell model, focusing on the $sd$-shell and neglecting residual three-body terms.

Findings

Reproduces properties of oxygen isotopes near the neutron dripline.

Highlights the importance of three-nucleon forces and continuum coupling.

Dissects contributions of different chiral three-nucleon force components.

Abstract

Three-nucleon force and continuum play important roles in reproducing the properties of atomic nuclei around driplines. Therefore it is valuable to build up a theoretical framework where both effects can be taken into account to solve the nuclear Schr\"odinger equation. To this end, in this letter, we have expressed the chiral three-nucleon force within the continuum Berggren representation, so that bound, resonant and continuum states can be treated on an equal footing in the complex-momentum space. To reduce the model dimension and computational cost, the three-nucleon force is truncated at the normal-ordered two-body level and limited in the $sd$-shell model space, with the residual three-body term being neglected. We choose neutron-rich oxygen isotopes as the test ground because they have been well studied experimentally, with the neutron dripline determined. The calculations have been carried out within the Gamow shell model. The quality of our results in reproducing the properties of oxygen isotopes around the neutron dripline shows the relevance of the interplay between three-nucleon force and the coupling to continuum states. We also analyze the role played by the chiral three-nucleon force, by dissecting the contributions of the $2\pi$ exchange, $1\pi$ exchange and contact terms.