Heavy Neutral Leptons -- Advancing into the PeV domain

Abstract

Heavy neutral leptons (HNLs) are hypothetical particles able to explain neutrino oscillations and provide a mechanism for generating the baryon asymmetry of the Universe. Quantum corrections due to such particles give rise to flavor violating processes in the charged lepton sector. Based on the fact that these corrections grow with HNL masses, we improve existing constraints by orders of magnitude in mass and mixing angle. This allows us to probe part of the parameter space of leptogenesis with multi-TeV HNLs. We also show that one will be able to infer HNL parameters in a significant portion of the parameter space for TeV-PeV masses if charged lepton flavor violating signals are detected.