Some algebraic structures for the bosonic three-level systems

A simple systematic procedure to construct the three-level unitary and orthogonal algebras which appear in the bosonic three -level pairing models and for arbitrary choice of level degeneracies is presented. We draw attention to the existence of the three types of dynamical symmetry. The new analytical expressions of the energies are derived. The results presented show very clearly the duality between orthogonal algebras and the quasi-spin algebras for the three-level system with pairing interactions. The seniority selection rules of the transition operators in three level boson system are given. Illustrative calculations are carried out for U 21 algebra.