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arXiv · 2512.09272

Anomalous collective modes in atomic nuclei within the proton-neutron interacting boson model

Wei Teng·Yu Zhang·Sheng-Nan Wang·Feng Pan·Chong Qi·J. P. Draayer
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Abstract

Novel collective modes characterized by a $B_{4/2}$ ratio ($\equiv B(E2;4_1^+\rightarrow 2_1^+)/B(E2;2_1^+\rightarrow 0_1^+)$) less than 1.0 that were observed recently have been identified within the proton-neutron interacting boson model (IBM-2) using the consistent-$Q$ Hamiltonian. These modes are shown to give rise to triaxial spectral features, including significant band mixing. The results provide a compelling explanation for the deeply suppressed $B_{4/2}$ ratio observed in $^{166}$W, $^{168,170}$Os, and $^{172}$Pt, offering new insights into the $B(E2)$ anomaly phenomenon in neutron-deficient nuclei.

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Wei Teng, Yu Zhang, Sheng-Nan Wang, Feng Pan, Chong Qi, J. P. Draayer. 2025-12-10. Anomalous collective modes in atomic nuclei within the proton-neutron interacting boson model. https://doi.org/10.1016/j.physletb.2025.139487

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