Leptogenesis Bound on Spontaneous Symmetry Breaking of Global Lepton Number

TL;DR

This paper establishes bounds on the spontaneous breaking of global lepton number in leptogenesis models, emphasizing the role of Majorons and their impact on neutrino interactions and early universe processes.

Contribution

It introduces new leptogenesis bounds related to spontaneous lepton number breaking and analyzes specific Majoron models to determine the necessary symmetry breaking scale.

Findings

Lepton number must be broken above 10^5 GeV for successful leptogenesis.

Right-handed neutrino annihilations into Majorons and Higgs must be out of equilibrium.

Constraints apply to various Majoron and R-parity violating supersymmetric models.

Abstract

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.