  We incorporate the parameters of the gauge group G into the gauge theory of
interactions through a non-linear partial-trace sigma-model Lagrangian on G/H.
The minimal coupling of the new (Goldstone-like) scalar bosons provides mass
terms to those intermediate vector bosons associated with the quotient G/H,
without spoiling gauge invariance, remaining the H-vector potentials massless.
The main virtue of a partial trace on G/H, rather than on the entire G, is that
we can find an infinite-dimensional symmetry, with non-trivial Noether
invariants, which ensures quantum integrability in a non-canonical quantization
scheme. The present formalism is explicitly applied to the case G=SU(2)x U(1),
as a Higgs-less alternative to the Standard Model of electroweak interactions,
although it can also be used in low-energy phenomenological models for strong
interactions.
