Transition probabilities in the $U(3,3)$ limit of the symplectic IVBM
  The tensor properties of the algebra generators are determined in respect to the reduction chain $Sp(12,R) \supset U(3,3) \supset U_{p}(3) \otimes \overline{U_{n}(3)}\supset U^{\ast}(3) \supset O(3)$, which defines one of the dynamical symmetry limits of the Interacting Vector Boson Model (IVBM). The symplectic basis according to the considered chain is thus constructed and the action of the $Sp(12,R)$ generators as transition operators between the basis states is illustrated. The matrix elements of the $U(3,3)$ ladder operators in the so obtained symmetry-adapted basis are given. The $U(3,3)$ limit of the model is further tested on the more complicated and complex problem of reproducing the $B(E2)$ transition probabilities between the collective states of the ground band in $^{104}Ru$, $^{192}Os$, $^{192}Pt$, and $^{194}Pt$ isotopes, considered by many authors to be axially asymmetric. Additionally, the excitation energies of the ground and $\gamma$ bands in $^{104}Ru$ are calculated. The theoretical predictions are compared with the experimental data and some other collective models which accommodate the $\gamma-$rigid or $\gamma-$soft structures. The obtained results reveal the applicability of the model for the description of the collective properties of nuclei, exhibiting axially asymmetric features. 
H. G. Ganev
nucl-th