A new physical basis for the irreducible representations of the orthogonal group SO(5) in the quasi-spin formalism

New physical state vectors for the irreducible representations of the group SO(5) are constructed in an analytical form. The state vectors are labelled by the quantum numbers of the isospin, its third component, by the number of particles and by a fourth properly defined quantum number. The previously constructed bases have been compared with the new construction from the same point of view. Two examples illustrate the new construction. (author)