Signatures of Dirac and Majorana Sterile Neutrinos in Trilepton Events at the LHC

Understand

Heavy sterile neutrinos with masses below $M_W$ can induce trilepton events at the 14 TeV LHC through purely leptonic $W$ decays of $W^\pm \to e^\pm e^\pm \mu^\mp \nu$ and $\mu^\pm \mu^\pm e^\mp \nu$ where the heavy neutrino will be in an intermediate state on its mass shell.

• Discovery and exclusion limits for the heavy neutrinos are found using both Cut-and-Count (CC) and a Multi-Variate Analysis (MVA) methods in this study.
• We also show that it is possible to discriminate between a Dirac and a Majorana heavy neutrino, even when lepton number conservation cannot be directly tested due to unobservability of the final state neutrino.
• This discrimination is done by exploiting a combined set of kinematic observables that differ between the Majorana vs.