Search for heavy lepton partners of neutrinos in proton-proton collisions in the context of the type III seesaw mechanism

TL;DR

This paper reports a search for heavy lepton partners of neutrinos predicted by type III seesaw models in proton-proton collisions, setting new lower mass limits based on CMS data at 7 TeV.

Contribution

First experimental limits on type III seesaw fermionic triplet states from LHC data, constraining their masses between 180 and 210 GeV.

Findings

No excess events observed above standard model background.

Set lower mass limits for heavy neutrino partners ranging from 180 to 210 GeV.

First LHC experiment to report limits on type III seesaw fermionic triplets.

Abstract

A search is presented in proton-proton collisions at sqrt(s) = 7 TeV for fermionic triplet states expected in type III seesaw models. The search is performed using final states with three isolated charged leptons and an imbalance in transverse momentum. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 4.9 inverse femtobarns. No excess of events is observed above the background predicted by the standard model, and the results are interpreted in terms of limits on production cross sections and masses of the heavy partners of the neutrinos in type III seesaw models. Depending on the considered scenarios, lower limits are obtained on the mass of the heavy partner of the neutrino that range from 180 to 210 GeV. These are the first limits on the production of type III seesaw fermionic triplet states reported by an experiment at the LHC.