Leptogenesis with Composite Neutrinos

TL;DR

This paper explores models with composite singlet neutrinos that can generate small neutrino masses and facilitate leptogenesis, including novel low-scale Dirac leptogenesis scenarios at around 10 TeV.

Contribution

It provides UV completions for composite neutrino models and demonstrates their potential for both Majorana and Dirac leptogenesis, including low-scale realizations.

Findings

Models can produce small neutrino masses via non-renormalizable terms.

Standard leptogenesis possible with Majorana masses.

Dirac leptogenesis feasible at scales as low as 10 TeV.

Abstract

Models with composite singlet neutrinos can give small Majorana or Dirac masses to the active neutrinos. The mechanism is based on the fact that conserved chiral symmetries give massless neutrinos at the renormalizable level. Thus, they acquire very small masses due to non-renormalizable terms. We investigate such models in two aspects. First, we find UV completions for them and then we investigate the possibility of giving leptogenesis. We find that these models offer new possibilities for leptogenesis. Models with Majorana masses can exhibit standard leptogenesis. Models with Dirac masses can provide a realization of Dirac type leptogenesis with mass scale that can be as low as 10 TeV.