A Natural Nightmare for the LHC?

摘要

A minimal lepton number conserving extension to the Standard Model is considered providing light Dirac neutrinos without resorting to tiny Yukawa couplings. Successful baryogenesis through leptogenesis is not only possible in this case, but even suggests an electroweak scale vacuum expectation value for a gauge singlet scalar in the model. The spectrum contains two massive Higgs bosons and a massless Nambu-Goldstone boson. The existence of the Nambu-Goldstone boson suppresses the Higgs to b branching ratio and instead Higgs bosons will decay mainly into invisible Goldstone bosons. We consider the constraints on the potential and the implications for the LHC.