Leptogenesis from Heavy Right-Handed Neutrinos in CPT Violating Backgrounds

Understand

We discuss leptogenesis in a model with heavy right-handed Majorana neutrinos propagating in a constant but otherwise generic CPT-violating axial time-like background (which could be motivated by string theory considerations).

• At temperatures much higher than the temperature of the electroweak phase transition we solve analytically but approximately (using Pade approximants) the corresponding Boltzmann equations, which describe lepton asymmetry generation due to the tree-level decays of the heavy neutrinos into standard model leptons.
• These leptons are effectively massless at such temperatures.
• The current work completes in a rigorous way a preliminary treatment of the same system, by some of the present authors.