Naturalness, Vacuum Stability and Leptogenesis in the Minimal Seesaw Model

TL;DR

This paper explores the minimal type-I seesaw model with two degenerate right-handed neutrinos, analyzing naturalness, vacuum stability, lepton flavor violation, and leptogenesis, and discusses implications for neutrinoless double beta decay.

Contribution

It provides a comprehensive comparison of naturalness, vacuum stability, and lepton flavor violation constraints in the minimal seesaw model, including perturbations for successful leptogenesis.

Findings

Naturalness constrains right-handed neutrino masses and Yukawa couplings.

Vacuum stability limits are compatible with naturalness bounds.

Small perturbations enable successful leptogenesis.

Abstract

The right-handed neutrinos within the type-I seesaw mechanism can induce large radiative corrections to the Higgs mass, and naturalness arguments can then be used to set limits on their mass scale and Yukawa couplings. Driven by minimality, we consider the presence of two degenerate right-handed neutrinos. We compare the limits from naturalness with the ones from the stability of the electroweak vacuum and from lepton flavor violation. Implications from neutrinoless double beta decay are also discussed and renormalization effects for the light neutrino parameters are presented. Adding small perturbations to the degenerate heavy neutrino spectrum allows for successful leptogenesis.