Phenomenology and cosmology of extra generations of Higgs bosons

If the Higgs sector (like the fermion sector) in a supersymmetric model consists of several generations, then a basis in which only one generation gets vacuum values can be chosen. The other generations have been largely ignored, but can be interesting. For example, in the minimal model, if tree-level flavor-changing neutral currents are eliminated by some symmetry, then the lightest of these scalars is stable and the second lightest is only slightly more massive. The lightest is a superb dark-matter candidate, and if light enough, gives an unusual and detectectable signature at the SLAC Linear Collider or the CERN $e^{+}$ $e^{\mathrm{-}}$ collider LEP.