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arXiv · 2511.22227

Study of $0^+$ and $8^-$ states in even-even $^{250-260}$No isotopes

M. A. Mardyban·V. O. Nesterenko
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Abstract

Low-lying $K^{\pi}=0^+$ and isomeric $8^-$ states in even-even isotopes $^{250-260}$No are explored within the Quasiparticle Random-Phase Approximation (QRPA) method with Skyrme parametrization SLy4. The deformations, single-particle (s-p) spectra and pairing in the isotopes are inspected. The calculations predict a pronounced minimum in the neutron pairing at $A$=252, 254, which significantly affects the properties of $0^+$ and $8^-$ states and leads to a correlation of their spectra. It is shown that $8^-$ isomers are basically low-energy two-quasiparticle (2qp) states. The appearance or absence of these isomers in $^{250-260}$No is explained as a combined effect of the s-p spectra and pairing. The collective $0^+$ states are predicted in all the isotopes as the lowest multipole non-rotational excitations. These states are interpreted as a superposition of pairing vibrations and $\beta$-vibrations. The results are in a reasonable agreement with available experimental data for $^{252,254}$No.

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M. A. Mardyban, V. O. Nesterenko. 2025-11-27. Study of $0^+$ and $8^-$ states in even-even $^{250-260}$No isotopes. https://arxiv.org/abs/2511.22227

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