CP Violation and Baryogenesis due to Heavy Majorana Neutrinos
Apostolos Pilaftsis
TL;DR
This work addresses how baryogenesis can proceed via leptogenesis from out-of-equilibrium decays of heavy Majorana neutrinos, focusing on resonant CP violation arising from mixing of nearly degenerate states. It develops a field-theoretic resummation framework for decay amplitudes, derives renormalized two-state mixing amplitudes, and analyzes both epsilon- and epsilon'-type CP asymmetries, including finite-temperature considerations. Numerical Boltzmann-equation studies show that the observed BAU can be achieved for heavy-neutrino masses ranging from ∼1 TeV to the GUT scale, with resonant enhancement occurring when mass splittings are of order the widths. The results indicate weak low-energy constraints and robust viability of resonant leptogenesis across a broad parameter space, with testable implications for collider phenomenology and GUT-embedded models.
Abstract
We analyze the scenario of baryogenesis through leptogenesis induced by the out-of-equilibrium decays of heavy Majorana neutrinos and pay special attention to CP violation. Extending a recently proposed resummation formalism for two-fermion mixing to decay amplitudes, we calculate the resonant phenomenon of CP violation due to the mixing of two nearly degenerate heavy Majorana neutrinos. Solving numerically the relevant Boltzmann equations, we find that the isosinglet Majorana mass may range from 1 TeV up to the grand unification scale, depending on the mechanism of CP violation and/or the flavour structure of the neutrino mass matrix assumed. Finite temperature effects and possible constraints from the electric dipole moment of electron and other low-energy experiments are briefly discussed.