Majorana vs. Dirac sterile neutrinos at the LHC

We study leptonic decays W^± → e^±e^{± ∓} and W^± → ^{± ±}e^∓ which would occur at the LHC if there exist sterile neutrinos with masses below M_W . We also study ways to discriminate their Majorana or Dirac character, a rather non trivial task, because lepton number conservation cannot be checked due to the missing neutrino in the final state. We find that it is indeed possible to discriminate between Majorana vs. Dirac sterile neutrinos by comparing the production of e^±e^{± ∓} vs. ^{± ±}e^∓ if the N-e and N- mixings are sufficiently different. Alternatively, one could also distinguish the Majorana vs. Dirac character by studying the energy spectra of the opposite charge lepton, a method that works even for equal N-e and N- mixings.