Beyond the MSSM
  Specific quasi-realistic superstring constructions often predict the existence of new TeV-scale physics which may be different in character from bottom-up motivated constructions. I describe examples of such beyond the MSSM physics, with special emphasis on heavy Z' gauge bosons and associated exotic particles. Implications of an extra U(1)' include a viable scienario for electroweak baryogenesis, a highly non-standard light Higgs sector, and Z'-mediated contributions to rare B decays. 
Paul Langacker