Description of Mixed-mode Dynamics with Symplectic Interacting Vector Boson Model

摘要

The symplectic extension to Sp(12,R) of the unitary dynamical symmetry U(6))U(3) U(2)) O(3) U(1) of the Interacting Vector Boson Model /IVBM/, that has been used for a description of only - well deformed even-even nuclei is shown to also provide for the larger possibility of a description of mixed-mode dynamics in this particular limit. This is due to the introduction of the dependence on the total number of the two kinds of bosons in the model Hamiltonian, as well as in the basis states from which they are built and than mapped onto the experimentally observed collective bands in nuclear spectra. Another advantage of the proposed model is the introduced algebraic definition of opposite parity states, which allows the description of bands of positive and negative parity. The larger limits of applications are demonstrated with examples of various types of heavy nuclei ranging from nearly spherical trough transitional to well deformed ones and for a the description of the key collective bands, starting from the yrast band and its relation to the excited K~π=0~+ γ- and K~π=0~+ bands. An improved description of the E2 transition probabilities in the yrast bands up to very high spins is achieved as a result of the introduced symplectic terms in the transition operators. The systematic investigation of this behavior in sequences of nuclei could lead to a better understanding of the critical phenomena observed in specific regions of the nuclear chart.