ATLAS Collab.
Search for third-generation vector-like leptons in pp collisions at √s=13TeV with the ATLAS detector
A search for vector-like leptons in multilepton (two, three, or four-or-more electrons plus muons) final states with zero or more hadronic τ-lepton decays is presented. The search is performed using a dataset of proton−proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 fb−1. To maximize the separation of signal and background, a machine-learning classifier is used. No excess of events is observed beyond the Standard Model expectation. Using a doublet vector-like lepton model, vector-like leptons coupling to third-generation Standard Model leptons are excluded in the mass range from 130 GeV to 900 GeV at the 95% confidence level, while the highest excluded mass is expected to be 970 GeV.