On the Minimal Mixing of Heavy Neutrinos

Abstract

We revisit the constraints on the properties of right handed neutrinos from the requirement to explain the observed light neutrino oscillation data in the type-I seesaw model. We use well-known relations to show that there is in general no lower bound on the mixing of a given heavy neutrino with any individual Standard Model generation. Lower bounds quoted in the literature only apply if the masses of the heavy neutrinos are so degenerate that they cannot be distinguished experimentally. A lower bound on the total mixing (summed over Standard Model generations) can be derived for each heavy neutrino individually, but it strongly depends on the mass of the lightest Standard Model neutrino and on the number of heavy neutrinos that contribute to the seesaw mechanism. Our results have implications for the perspectives of future colliders or fixed target experiments to rule out certain mass ranges for heavy neutrinos.

Typos corrected and references added, 13 pages plus appendix, one figure

References in corpus (19)

• The Standard Model Higgs boson as the inflaton
• Light Sterile Neutrinos: A White Paper
• Matter and Antimatter in the Universe
• How to find neutral leptons of the nuMSM?
• Minimal Flavour Seesaw Models
• A facility to Search for Hidden Particles (SHiP) at the CERN SPS
• A possible symmetry of the $\nu$MSM
• Sterile Neutrinos as the Origin of Dark and Baryonic Matter
• Multilepton and Lepton Jet Probes of Sub-Weak-Scale Right-Handed Neutrinos
• Baryon Asymmetry of the Universe in the NuMSM
• Sterile neutrino searches via displaced vertices at LHCb
• Same Sign versus Opposite Sign Dileptons as a Probe of Low Scale Seesaw Mechanisms
• Probing leptogenesis with GeV-scale sterile neutrinos at LHCb and BELLE II
• $N_{\mathrm{eff}}$ in low-scale seesaw models versus the lightest neutrino mass
• Distinguishing Dirac/Majorana Sterile Neutrinos at the LHC
• Nearly degenerate heavy sterile neutrinos in cascade decay: mixing and oscillations
• Lepton number violation by heavy Majorana neutrino in $B$ decays
• Equivalence between massless neutrinos and lepton number conservation in fermionic singlet extensions of the Standard Model
• Probing baryon asymmetry of the Universe at LHC and SHiP

Cited by in corpus (2)

• Distinguishing Dirac and Majorana Heavy Neutrinos at Lepton Colliders
• Naturalness in Soft Leptogenesis and Gravitino Mass Bound due to Primordial Black Holes