We investigate the hypernuclear cluster states of Λ9−11Be and Λ12B using the Control Neural Networks (Ctrl.NN) method,which demonstrates rapid convergence in basis state selection compared to traditional GCM calculations. For Λ9−11Be,the numerical results reproduce ground state energies and rotational bands consistent with experiments, revealing a short-range repulsive correlation between the Λ particle and α clusters,leading to a broad Λ distribution termed an “”analog pi-orbit”” structure. For Λ12B, we extend the Ctrl.NN method to calculate the positive-parity spectrum, incorporating sd-shell excitations and parity-coupling effects. Structural changes, including clustering effects and new configurations such as isosceles-triangle and α-t-α linear-chain structures, are revealed. Experimental peaks #6 and #8 are identified as p-Λ dominant states, consistent with shell-model predictions, and candidates for unexplained peaks are proposed. Cluster-shell competition, driven by nuclear forces and Pauli blocking, is found to be critical in Λ12B, where low-lying states exhibit shell-like structures, while clustered states near the α+α+t threshold show broad distributions. The third 3/2− state is identified as an analog Hoyle state, providing a platform to study cluster-breaking effects through binding energy, radius, and γ-transition analyses. These results highlight the interplay between cluster formation, Λ-induced modifications, and unified descriptions of nuclear structure via advanced models like Ctrl.NN.
References:
[1] J. Tian, Z. Cheng, C. Yu, M. Lyu, T. Myo et al., Phys. Lett. B 855,138816 (2024).
[2] Z. Cheng, M. Lyu, T. Myo et al., arXiv:2406.15060.
[3] M. Iodice, F. Cusanno, A. Acha, et al., Phys. Rev. Lett. 99, 052501 (2007).
*Remark:
This seminar is included in KEK Theory Center one-day workshop “Nuclear Physics with Strangeness and Clusters”.
(https://kds.kek.jp/event/53383/)