Mass Bounds on Light and Heavy Neutrinos from Radiative MFV Leptogenesis

TL;DR

This paper establishes new constraints on neutrino masses and lepton number violation scales within MFV leptogenesis, linking high-energy theory parameters to low-energy experimental tests.

Contribution

It provides the first comprehensive bounds on light and heavy neutrino masses considering radiative effects in MFV leptogenesis, avoiding previous no-go limitations.

Findings

Lightest neutrino mass must be below ~0.05 eV.

Majorana scale of lepton number violation exceeds ~10^{12} GeV.

Potential to probe new MFV scales up to ~100 TeV in low-energy experiments.

Abstract

We derive novel limits on the masses of the light and heavy Majorana neutrinos by requiring successful leptogenesis in seesaw models of minimal flavour violation (MFV). Taking properly into account radiative flavour effects and avoiding the limitations due to a no-go theorem on leptonic asymmetries, we find that the mass of the lightest of the observable neutrinos must be smaller than $\sim 0.05$ eV, whilst the Majorana scale of lepton number violation should be higher than $\sim 10^{12}$ GeV. The latter lower bound enables one to probe the existence of possible new scales of MFV, up to energies of $\sim 100$ TeV, in low-energy experiments, such as $\mu \to e\gamma$ and $\mu \to e$ conversion in nuclei. Possible realizations of MFV leptogenesis in Grand Unified Theories are briefly discussed.