MeV-scale Seesaw and Leptogenesis

Understand

We study the type-I seesaw model with three right-handed neutrinos and Majorana masses below the pion mass.

• In this mass range, the model parameter space is not only strongly constrained by the requirement to explain the light neutrino masses, but also by experimental searches and cosmological considerations.
• In the existing literature, three disjoint regions of potentially viable parameter space have been identified.
• In one of them, all heavy neutrinos decay shortly before big bang nucleosynthesis.