Triaxial shapes in the interacting vector boson model

A new dynamical symmetry limit of the two-fluid interacting vector boson model (IVBM), defined through the chain Sp(12,R) superset of U(3,3) superset of U*(3) x SU(1,1) superset of SU*(3) superset of SO(3), is introduced. The SU*(3) algebra considered in the present paper closely resembles many properties of the SU*(3) limit of the interacting boson model-2, which have been shown by many authors geometrically to correspond to the rigid triaxial model. The influence of different types of perturbations on the SU*(3) energy surface, in particular the addition of a Majorana interaction and an O(6) term to the model Hamiltonian, is studied. The effect of these perturbations results in the formation of a stable triaxial minimum in the energy surface of the IVBM Hamiltonian under consideration. Using a schematic Hamiltonian that possesses a perturbed SU*(3) dynamical symmetry, the theory is applied for the calculation of the low-lying energy spectrum of the nucleus 192Os. The theoretical results obtained agree reasonably with the experimental data and show a very shallow triaxial minimum in the energy surface for the ground state in 192Os, suggesting that the proposed dynamical symmetry might be appropriate for the description of the collective properties of different nuclei, exhibiting triaxial features.