Phenomenology and cosmology of second- and third-family Higgs bosons

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Abstract
We study the possibility that the Higgs sector of the minimal supersymmetric model consists of three families in the same manner that the fermion sector does. Including only extra doublets and assuming that tree-level flavor-changing neutural currents are naturally eliminated by some symmetry, we find that the lightest of the new scalars is absolutely stable, and that the second lightest is only about 1 GeV more massive. The coupling of these scalars to the Z is independent of any new parameters and if light enough they could be easily discovered (or ruled out) if a search is made for the somewhat unusual signature. The natural stability of the lightest scalar makes it an excellent dark-matter candidate, although the near mass degeneracy of the lightest two of these scalars makes the standard calculational method inadequate.