Characterisation at the HL-LHC of Long-lived Heavy Neutrinos in Gauge Extensions of the Standard Model

We show how signals of heavy neutrinos with displaced decays can be detected at the Large Hadron Collider in two theoretical setups, both exploiting extended gauge sectors as portals to such new physics, the Left-Right Symmetric Model and $U(1{)}_{B-L}$. Further, owing to the reduced contamination from backgrounds away from the interaction point, we illustrate how the properties of the heavy neutrinos (mass, width and quantum numbers) can neatly be accessed at the High-Luminosity upgrade of the CERN machine.