Bubbles in $^{34}$Si and $^{22}$O?

TL;DR

This study investigates the existence of bubble nuclei, specifically $^{34}$Si and $^{22}$O, using multiple theoretical models to assess their central density depletion and potential bubble structure.

Contribution

The paper compares three theoretical frameworks to identify candidate bubble nuclei, providing evidence supporting $^{34}$Si as a proton bubble nucleus.

Findings

All models agree on a 40% proton density depletion in $^{34}$Si.

Model dependence questions the bubble structure of $^{22}$O.

Strong evidence for a proton bubble in $^{34}$Si.

Abstract

Bubble nuclei are characterized by a depletion of their central density. Their existence is examined within three different theoretical frameworks: the shell model as well as non-relativistic and relativistic microscopic mean-field approaches. We propose $^{34}$Si and $^{22}$O as possible candidates for proton and neutron bubble nuclei, respectively. In the case of $^{22}$O, we observe a significant model dependence, thereby calling into question the bubble structure of $^{22}$O. In contrast, an overall agreement among the models is obtained for $^{34}$Si. Indeed, all models predict a central proton density depletion of about 40%. This result provides strong evidence in favor of a proton bubble in $^{34}$Si.