  The possibility of non-trivial representations of the gauge group on
wavefunctionals of a gauge invariant quantum field theory leads to a generation
of mass for intermediate vector and tensor bosons. The mass parameters m show
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 that
massless bosons need to form massive bosons. This is a `non-Higgs' mechanism
that could provide new clues for the best understanding of the symmetry
breaking mechanism in unified field theories. A unified quantization of
massless and massive non-Abelian Yang-Mills, linear Gravity and Abelian
two-form gauge field theories are fully developed from this new approach, where
a cohomological origin of mass is pointed out.
