Heavy Z bosons and Majorana neutrinos

Several extensions of the standard model predict the existence of additional Z bosons, which could possibly be in the 100-400 GeV range. In these schemes the new gauge boson is generally strongly coupled to heavy Majorana neutrinos which have highly distinctive decay modes. Amongst these are like-sign dileptons and monojets. We present an analysis of the system and discuss the implications for future hadron and e+e- colliders. Combining the results of our study with constraints from neutral current and collider data, we show that the CERN monojets cannot be explained by this system. (orig.)