Combining Experimental and Cosmological Constraints on Heavy Neutrinos

TL;DR

This paper comprehensively combines experimental and cosmological data to constrain heavy neutrinos in the mass range between pions and W bosons, providing a unified analysis for future searches.

Contribution

It is the first to integrate direct, indirect, and cosmological constraints on heavy neutrinos within this specific mass range.

Findings

Big bang nucleosynthesis strongly constrains heavy neutrino properties.

The results inform the discovery potential at LHCb, BELLE II, SHiP, ATLAS, CMS, and future colliders.

Abstract

We study experimental and cosmological constraints on the extension of the Standard Model by three right handed neutrinos with masses between those of the pion and W boson. We combine for the first time direct, indirect and cosmological constraints in this mass range. This includes experimental constraints from neutrino oscillation data, neutrinoless double $\beta$ decay, electroweak precision data, lepton universality, searches for rare lepton decays, tests of CKM unitarity and past direct searches at colliders or fixed target experiments. On the cosmological side, big bang nucleosynthesis has the most pronounced impact. Our results can be used to evaluate the discovery potential of searches for heavy neutrinos at LHCb, BELLE II, SHiP, ATLAS, CMS or a future lepton collider.