Probing the two-quasiparticle $K^π=8^+$ isomeric structure and enhanced stability in the proton drip-line nuclei

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Main Authors: Zhang, Zhen-Zhen, Wang, Hua-Lei, Xiao, Kui, Liu, Min-Liang
Format: Preprint
Published: 2026
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author Zhang, Zhen-Zhen
Wang, Hua-Lei
Xiao, Kui
Liu, Min-Liang
author_facet Zhang, Zhen-Zhen
Wang, Hua-Lei
Xiao, Kui
Liu, Min-Liang
contents Stimulated by recent experimental discoveries [{Phys. Lett. B \textbf{847}, 138310 (2023)} and {Phys. Rev. Lett. \textbf{132}, 072502 (2024)}], two-quasiparticle $K^π=8^+$ isomeric structure (related to the neutron $h_{9/2}$ and $f_{7/2}$ orbitals) in $^{160}_{76}$Os$_{84}$ that lies at the two-proton drip line has been studied by means of the configuration-constrained potential-energy-surface calculations. Calculated results indicate that, for such an isomer, the excitation energy can be well reproduced and its oblate shape can be enhanced by the polarization effects of the two high-$K$ orbits. Comparing with experimental data, two sets of the widely used Woods-Saxon parameters, especially, the spin-orbit coupling one, are evaluated and argued. It is found that, considering the uncertainty of the spin-orbit coupling strength, the energy crossing or inversion of the $h_{9/2}$ and $f_{7/2}$ neutrons can occur, which may lead to three kinds of different evolution-trends of two-quasiparticle excitation energies with the changing quadrupole deformation $β_2$. With decreasing spin-orbit coupling interaction, the structure of the $K^π=8^+$ isomeric state will evolute from $νh_{9/2}f_{7/2}$ ($ν9/2^-[505] \otimes 7/2^-[503]$) to the mixing of $νh_{9/2}f_{7/2}$ and $νh_{9/2}^2$ ($ν9/2^-[505] \otimes 7/2^-[514]$) to $νh_{9/2}^2$, indicating that its structural probes is still of interest and an arbitrary assignment may be risky. The related theoretical calculations and experimental evidences e.g., the transition properties, are desirable. In addition, similar to that in superheavy nuclei, it is suggested that the stability inversion between high-$K$ isomeric states and ground states might occur in this proton drip-line mass region, e.g., in the hitherto unknown nucleus $^{162}_{78}$Pt$_{84}$.
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id arxiv_https___arxiv_org_abs_2601_09526
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Probing the two-quasiparticle $K^π=8^+$ isomeric structure and enhanced stability in the proton drip-line nuclei
Zhang, Zhen-Zhen
Wang, Hua-Lei
Xiao, Kui
Liu, Min-Liang
Nuclear Theory
Stimulated by recent experimental discoveries [{Phys. Lett. B \textbf{847}, 138310 (2023)} and {Phys. Rev. Lett. \textbf{132}, 072502 (2024)}], two-quasiparticle $K^π=8^+$ isomeric structure (related to the neutron $h_{9/2}$ and $f_{7/2}$ orbitals) in $^{160}_{76}$Os$_{84}$ that lies at the two-proton drip line has been studied by means of the configuration-constrained potential-energy-surface calculations. Calculated results indicate that, for such an isomer, the excitation energy can be well reproduced and its oblate shape can be enhanced by the polarization effects of the two high-$K$ orbits. Comparing with experimental data, two sets of the widely used Woods-Saxon parameters, especially, the spin-orbit coupling one, are evaluated and argued. It is found that, considering the uncertainty of the spin-orbit coupling strength, the energy crossing or inversion of the $h_{9/2}$ and $f_{7/2}$ neutrons can occur, which may lead to three kinds of different evolution-trends of two-quasiparticle excitation energies with the changing quadrupole deformation $β_2$. With decreasing spin-orbit coupling interaction, the structure of the $K^π=8^+$ isomeric state will evolute from $νh_{9/2}f_{7/2}$ ($ν9/2^-[505] \otimes 7/2^-[503]$) to the mixing of $νh_{9/2}f_{7/2}$ and $νh_{9/2}^2$ ($ν9/2^-[505] \otimes 7/2^-[514]$) to $νh_{9/2}^2$, indicating that its structural probes is still of interest and an arbitrary assignment may be risky. The related theoretical calculations and experimental evidences e.g., the transition properties, are desirable. In addition, similar to that in superheavy nuclei, it is suggested that the stability inversion between high-$K$ isomeric states and ground states might occur in this proton drip-line mass region, e.g., in the hitherto unknown nucleus $^{162}_{78}$Pt$_{84}$.
title Probing the two-quasiparticle $K^π=8^+$ isomeric structure and enhanced stability in the proton drip-line nuclei
topic Nuclear Theory
url https://arxiv.org/abs/2601.09526