Spontaneous thermal Leptogenesis via Majoron oscillation

Understand

A novel model of spontaneous Leptogenesis is investigated, where it takes place in the thermal equilibrium due to a background Nambu-Goldstone field in motion.

• In particular, we identify the Nambu-Goldstone field to be the Majoron which associates with spontaneous breakdown of (discrete) $B-L$ symmetry.
• In this scenario sufficient lepton number asymmetry is generated in primordial thermal bath without having $CP$-violating out-of-equilibrium decay of the heavy right-handed Majorana neutrinos.
• To obtain the observed baryon asymmetry, the neutrino masses are predicted in certain ranges, which can be translated into the effective mass of the neutrinoless double beta decay.