Unveiling potential neutron halos in intermediate-mass nuclei: an \textit{ab initio} study

TL;DR

This study uses advanced ab ab initio bb methods to predict potential one- and two-neutron halo nuclei in intermediate-mass isotopes near the drip line, providing systematic theoretical insights into halo formation.

Contribution

It introduces a novel ab ab initio bb approach using spectroscopic factors and two-nucleon amplitudes to identify neutron halo candidates in medium-mass nuclei.

Findings

Identifies specific isotopes as promising one-neutron halo candidates.

Suggests certain isotopes as potential two-neutron halo nuclei.

Provides systematic predictions based on separation energies and occupation probabilities.

Abstract

Halos epitomize the fascinating interplay between weak binding, shell evolution, and deformation effects, especially in nuclei near the drip line. In this Letter, we apply the state-of-the-art \textit{ab initio} valence-space in-medium similarity renormalization group approach to predict potential candidates for one- and two-neutron halo in the intermediate-mass region. Notably, we use spectroscopic factors (SF) and two-nucleon amplitudes (TNA) as criteria for suggesting one- and two-neutron halo candidates, respectively. This approach is not only theoretically sound but also amenable to experimental validation. Our research focuses on Mg, Al, Si, P, and S neutron-drip-line nuclei, offering systematic predictions of neutron halo candidates in terms of separation energies, SF (TNA), and average occupation. The calculation suggests the ground states of $^{40,42,44,46}$Al, $^{41,43,45,47}$Si, $^{46,48}$P, and $^{47,49}$S are promising candidates for one-neutron halos, while $^{40,42,44,46}$Mg, $^{45,47}$Al, $^{46,48}$Si, $^{49}$P, and $^{50}$S may harbor two-neutron halos. In addition, the relative mean-square neutron radius between halo nuclei and \textit{inner core} is calculated for suggested potential neutron halos. Finally, the relations of halo formations and shell evolution are discussed.