Series of hadron energy levels as representations of non-compact groups

It has recently been emphasized [1] that in an approximate symmetry theory it is by no means necessary that a consistent relativistic model be available in which the symmetry is exact, with the violations then treated as perturbations. It is sufficient that a set of operators be found that obey the equal-time commutation relations characteristic of some algebra, that the energy operator be decomposed into terms transforming according to various irreducible representations of the algebra, and that the stationary and quasi-stationary quantum-mechanical states have a tendency to fall approximately into irreducible representations of the algebra as a result of dynamics. within each irreducible representations of the algebra as a result of dynamics