Ab-initio computation of neutron-rich oxygen isotopes

TL;DR

This study uses ab-initio methods to calculate the binding energies of neutron-rich oxygen isotopes, exploring how different nuclear interactions affect their stability, and highlights the importance of three-nucleon forces and continuum effects.

Contribution

It provides the first comprehensive ab-initio analysis of oxygen isotopes up to 28O using coupled-cluster methods and chiral interactions with different cutoffs.

Findings

28O is stable with a 500 MeV cutoff but unbound with 600 MeV cutoff.

Three-nucleon forces significantly influence isotope stability.

Continuum effects are crucial in accurate stability predictions.

Abstract

We compute the binding energy of neutron-rich oxygen isotopes and employ the coupled-cluster method and chiral nucleon-nucleon interactions at next-to-next-to-next-to-leading order with two different cutoffs. We obtain rather well-converged results in model spaces consisting of up to 21 oscillator shells. For interactions with a momentum cutoff of 500 MeV, we find that 28O is stable with respect to 24O, while calculations with a momentum cutoff of 600 MeV result in a slightly unbound 28O. The theoretical error estimates due to the omission of the three-nucleon forces and the truncation of excitations beyond three-particle-three-hole clusters indicate that the stability of 28O cannot be ruled out from ab-initio calculations, and that three-nucleon forces and continuum effects play the dominant role in deciding this question.