J. L. An | Searcharxiv

arXiv2025

Prediction of deformed halo nuclei $^{43,45}$Si from multiple criteria based on structure and reaction analyses

Possible deformed neutron halos in silicon isotopes are investigated from both structure and reaction perspectives using the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) combined with the Glauber model. The experimental neutron separation energies of silicon isotopes are well reproduced by the DRHBc theory. Multiple halo criteria are examined, including the global ones based on root-mean-square radii and density profiles, as well as the microscopic ones based on single-particle orbitals and their spatial distributions. Calculations employing different density functionals and pairing strengths consistently indicate the emergence of $p$-wave neutron halos in $^{43,45}$Si, accompanied by pronounced shape decoupling between the halo and the core. Moreover, the enhanced reaction cross sections and the narrow longitudinal momentum distributions of one-neutron removal residues provide additional evidence supporting the halo structures in $^{43,45}$Si.

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arXiv2023

Missed prediction of the neutron halo in $^{37}$Mg

Halo phenomena have long been an important frontier in both experimental and theoretical nuclear physics. $^{37}$Mg was identified as a halo nucleus in 2014 and remains the heaviest nuclear halo system to date. While the halo phenomenon in $^{37}$Mg was not predicted before the discovery, its description has been still challenging afterwards. In this Letter, we report a microscopic and self-consistent description of the neutron halo in $^{37}$Mg using the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) that was developed in 2010. The experimental neutron separation energies and empirical matter radii of neutron-rich magnesium isotopes as well as the deformed $p$-wave halo characteristics of $^{37}$Mg are well reproduced without any free parameters. In particular, the orbital occupied by the halo neutron in $^{37}$Mg, exhibiting $p$-wave components comparable to those suggested in experiments, remains consistent across various employed density functionals including PC-F1, PC-PK1, NL3*, and PK1. The DRHBc theory investigated only even-even magnesium isotopes in previous works and for that reason missed predicting $^{37}$Mg as a halo nucleus before 2014. Although the core and the halo of $^{37}$Mg are both prolate, higher-order shape decoupling on the hexadecapole and hexacontatetrapole levels is predicted.

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