Leptogenesis Bound on Spontaneous Symmetry Breaking of Global Lepton Number

Understand

We propose a new class of leptogenesis bounds on the spontaneous symmetry breaking of global lepton number.

• These models have a generic feature of inducing new lepton number violating interactions, due to the presence of the Majorons.
• We analyzed the singlet Majoron model with right-handed neutrinos and find that the lepton number should be broken above 10^5 GeV to realize a successful leptogenesis because the annihilations of the right-handed neutrinos into the massless Majorons and into the standard model Higgs should go out of equilibrium before the sphaleron process is over.
• We then argue that this type of leptogenesis constraint should exist in the singlet-triplet Majoron models as well as in a class of R-parity violating supersymmetric Majoron models.