Algebraic characterization of constraints and generation of mass in gauge theories

The possibility of non-trivial representations of the gauge group on wavefu nctionals of a gauge invariant quantum field theory leads to a generation o f mass for intermediate vector and tensor bosons. The mass parameters m sho w up as central charges in the algebra of constraints, which then become of second-class nature. The gauge group coordinates acquire dynamics outside the null-mass shell and provide the longitudinal field degrees of freedom t hat massless bosons need to form massive bosons.