Search for type-III seesaw heavy leptons in p p collisions at root s = 8 TeV with the ATLAS detector

Abstract

A search for the pair production of heavy leptons (N 0, L ±) predicted by the type-III seesaw theory formulated to explain the origin of small neutrino masses is presented. The decay channels N 0 → W ± l□(ℓ = e, μ, τ) and L ± → W ± ν (ν = ν e, ν μ, ν τ) are considered. The analysis is performed using the final state that contains two leptons (electrons or muons), two jets from a hadronically decaying W boson and large missing transverse momentum. The data used in the measurement correspond to an integrated luminosity of 20.3 fb - 1 of p p collisions at s = 8 TeV collected by the ATLAS detector at the LHC. No evidence of heavy lepton pair production is observed. Heavy leptons with masses below 325-540 GeV are excluded at the 95% confidence level, depending on the theoretical scenario considered.