Aad, G.G.AadAbbott, B.B.AbbottAbdallah, J.J.AbdallahAbdinov, O.O.AbdinovAben, R.R.AbenAbolins, M.M.AbolinsAbouZeid, O. S.O. S.AbouZeidAbramowicz, H.H.AbramowiczAbreu, H.H.AbreuAbreu, R.R.AbreuZwalinski, L.L.Zwalinski2015-03-112021-10-112015-03-112021-10-112015https://resolver.sub.uni-goettingen.de/purl?gro-2/90512Searches are performed for resonant and nonresonant Higgs boson pair production in the γγbb¯ final state using 20  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider. A 95% confidence level upper limit on the cross section times branching ratio of nonresonant production is set at 2.2 pb, while the expected limit is 1.0 pb. The difference derives from a modest excess of events, corresponding to 2.4 standard deviations from the background-only hypothesis. The limit observed in the search for a narrow X→hh resonance ranges between 0.7 and 3.5 pb as a function of the resonance mass.enCC BY 3.0https://creativecommons.org/licenses/by/3.0/Higgs Boson; ATLAS Detector530journal_article10.1103/PhysRevLett.114.08180225768755https://resolver.sub.uni-goettingen.de/purl?gs-1/11656openAccess