Searches for heavy neutrinos and heavy leptons

The discovery of non-zero neutrino masses has opened a new window for heavy neutrinos at TeV scale. The CMS experiment has performed many searches for heavy neutrinos at the LHC. We present an overview of these heavy neutrino (Majorana type) searches in events with two leptons and two jets or three leptons, using proton-proton collision data recorded by the CMS experiment.