Neutrinos at LHC - Results from CMS

Ideas beyond the standard model have been proposed to accomodate the finite values of neutrino masses inferred from oscillations among the three neutrino species. This presentation focuses on searches performed by the CMS collaboration at the LHC for heavy Majorana states predicted in seesaw models. Seesaw mechanisms involve fermionic weak-isospin singlets (type I) or scalar triplets (type II) or fermion triplets (type III). The searches are carried out in different final states containing two jets and two same-sign muons/electrons, or two jets and two muons/electons without charge requirements, or three charged, isolated leptons and an imbalance in trasverse momentum. The CMS data correspond to integrated luminosities of 5 $fb^{-1}$ in 2011 and 3.6 $fb^{-1}$ in 2012 of proton-proton collisions at the centre-of-mass energies of 7 TeV and 8 TeV, respectively. No excess of events is observed above the backgrounds predicted by the standard model, and the results are interpreted in terms of limits on the cross sections and masses of the new heavy particles expected in these models.