Broken SU(3) symmetry in deformed even-even nuclei

Abstract

A collective vector-boson model with broken SU(3) symmetry, in which the ground state band and the lowest $\gamma$ band belong to the same irreducible representation but are non-degenerate, is applied to several deformed even-even nuclei. The model description of ground and $\gamma$ bands together with the corresponding B(E2) transition probabilities is investigated within a broad range of SU(3) irreducible representations $(\lambda,\mu)$. The calculations show that the $(\lambda,\mu)$ characteristics of rotational nuclei depend to a great extent on the magnitude of the SU(3) splitting between the ground and $\gamma$ bands. It is found that for weakly split spectra, the ground--$\gamma$ band coupling scheme is realized relevantly within narrow regions of ``favored'' $(\lambda,\mu)$ multiplets, while in the cases of strong splitting a description in which the ground band is situated alone in an irreducible representation is favored. The obtained results are analyzed in terms of the bandmixing interactions. The possibility for a transition between the different collective SU(3) schemes is discussed.