Many extensions of the Standard Model have been proposed, and likely
this represents only a small number of what is possible.
Despite different underlying assumptions, many Beyond-the-Standard-Model
scenarios predict some common interactions or particles.
For instance, new 
and 
gauge bosons can
arise in a number of different ways. Therefore it makes sense
to cover a few basic classes of particles and interactions, with enough
generality that many kinds of detailed scenarios can be
accommodated by suitable parameter choices. We have already seen one
example of this, in the extended Higgs sector above. In this section
a few other kinds of non-standard generic physics scenarios are discussed.
Supersymmetry is covered separately in the following section,
since it is such a large sector by itself.