  We discuss possible symmetries of effective theories describing spinless and
spin 1 bosons, mainly to concentrate on an intriguing phenomenological
possibility: that of a hardly noticeable strong electroweak sector at
relatively low energies. Specifically, a model with both vector and axial
vector strong interacting bosons may possess a discrete symmetry imposing
degeneracy of the two sets of bosons (degenerate BESS model). In such a case
its effects at low energies become almost invisible and the model easily passes
all low energy precision tests. The reason lies essentially in the fact that
the model automatically satisfies decoupling, contrary to models with only
vectors. For large mass of the degenerate spin one bosons the model becomes
identical at the classical level to the standard model taken in the limit of
infinite Higgs mass. For these reasons we have thought it worthwhile to fully
develop the model, together with its possible generalizations, and to study the
expected phenomenology. For instance, just because of its invisibility at low
energy, it is conceivable that degenerate BESS has low mass spin one states and
gives quite visible signals at existing or forthcoming accelerators.
