Signals of heavy Majorana neutrinos at hadron colliders

The lepton number violating signal of like-sign dileptons (LSD), $p\overrightarrow{p}{l}^{\pm }{l}^{\pm }+2\mathrm{}$ jets, is investigated within a model of mixing in the neutrino sector assuming the existence of heavy Majorana neutrino states with a left-handed coupling to the light leptons. Helicity amplitudes are given pointing out differences with calculations previously reported by other authors. The signal cross sections are computed at the energy of the LHC $(\sqrt{S}=14\mathrm{}\mathrm{TeV})$ at CERN and within the existing experimental limits on the mixing couplings, including those coming from neutrinoless double beta decay.