Search for isosinglet heavy neutrinos at the CMS Collaboration

After the discovery of neutrino oscillations, the smallness of the Standard Model neutrino masses is one of the most intriguing questions in neutrino physics today. A leading theoretical candidate to explain this phenomenon is known as the "seesaw" mechanism, in which a new heavy Majorana neutrino (N) state is postulated. Here we present the recent efforts to search for this postulated heavy neutrino at the CMS collaboration using the LHC Run 2 data. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 137 fb-1. The variety of search strategies, covering various N production modes I.e., via charged current Drell-Yan, Wγ fusion and same-sign WW fusion processes, producing final states with two or three leptons and with different types of reconstructed jets, leads to a wide range of search sensitivity of N mass ranging from 1 GeV up to 25 TeV. We also discuss the future prospect of follow-up searches which are now vividly ongoing and expected to be published.