Symmetry and shape coexistence in 10Be

Within the low-lying spectrum of 10Be, multiple rotational bands are found, with strikingly different moments of inertia. A proposed interpretation has been that these bands variously represent triaxial rotation and prolate axially-deformed rotation. The bands are well-reproduced in ab initio no-core configuration interaction (NCCI) calculations. We use the calculated wave functions to elucidate the nuclear shapes underlying these bands, by examining the Elliott SU(3) symmetry content of these wave functions. The ab initio results support an interpretation in which the ground-state band, along with an accompanying K=2 side band, represent a triaxial rotor, arising from an SU(3) irreducible representation in the 0 hbar omega space. Then, the lowest excited K=0 band represents a prolate rotor, arising from an SU(3) irreducible representation in the 2 hbar omega space.Comment: 10 pages, 4 figures; contribution to the proceedings of the International Workshop "Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects" (SDANCA-21), Sofia, Bulgaria, September 2021; submitted to Bulg. J. Phy