Displaced vertex and disappearing track signatures in type-III seesaw

Abstract

We investigate a prospect of probing the type-III seesaw neutrino mass generation mechanism at various collider experiments by searching for a disappearing track and a displaced vertex signature originating from the decay of SU(2)_L triplet fermion (Sigma ). Since Sigma is primarily produced at colliders through the electroweak gauge interactions, its production rate is uniquely determined by its mass. We find that a Sigma particle produces a disappearing track signature from the decay of its charged component, which can be searched at the HL-LHC. Furthermore, we show that if the lightest observed neutrino has a mass of around 10^{-9} eV, the neutral component of {Sigma } can be discovered at the proposed MATHUSLA detector. We also show that the charged component of {Sigma } can be potentially be observed at FCC-he as a displaced vertex signature.