BROKEN SU(3) SYMMETRY IN DEFORMED EVEN-EVEN NUCLEI

A collective vector-boson model with broken SU(3) symmetry, in which t he ground-state band and the lowest gamma band belong to the same irre ducible representation but are nondegenerate, is applied to several de formed even-even nuclei. The model description of ground and gamma ban ds together with the corresponding B(E2) transition probabilities is i nvestigated within a broad range of SU(3) irreducible representations (lambda,mu). The calculations show that the (lambda,mu) characteristic s of rotational nuclei depend to a great extent on the magnitude of th e SU(3) splitting between the ground and gamma bands. It is found that for weakly split spectra, the ground-gamma band coupling scheme is re alized relevantly within narrow regions of ''favored'' (lambda,mu) mul tiplets, 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 band-mixin g interactions. The possibility for a transition between the different collective SU(3) schemes is discussed.