Search for the Standard Model Higgs boson in the decay channel H→ZZ (*) →4ℓ with 4.8 fb -1 of pp collision data at √s=7 TeV with ATLAS

Abstract

This Letter presents a search for the Standard Model Higgs boson in the decay channel H→ZZ (*) →ℓ + ℓ - ℓ '+ ℓ '- , where ℓ, ℓ ' =e or μ, using proton-proton collisions at √s=7 TeV recorded with the ATLAS detector and corresponding to an integrated luminosity of 4.8 fb -1 . The four-lepton invariant mass distribution is compared with Standard Model background expectations to derive upper limits on the cross section of a Standard Model Higgs boson with a mass between 110 GeV and 600 GeV. The mass ranges 134-156 GeV, 182-233 GeV, 256-265 GeV and 268-415 GeV are excluded at the 95% confidence level. The largest upward deviations from the background-only hypothesis are observed for Higgs boson masses of 125 GeV, 244 GeV and 500 GeV with local significances of 2.1, 2.2 and 2.1 standard deviations, respectively. Once the look-elsewhere effect is considered, none of these excesses are significant. © 2012 CERN.