Clark, Brian LeeFranklin, MelissaHuth, JohnIppolito, ValerioLazovich, TomoLopez Mateos, DavidMercurio, KevinMorii, MasahiroSpearman, WilliamSun, SiyuanTolley, EmmaTuna, AlexanderYen, AndyZambito, Stefano2017-09-062016ATLAS Collaboration. 2016. “Search for New Phenomena in Events With at Least Three Photons Collected in Pp Collisions at √s = 8 TeV With the ATLAS Detector.” The European Physical Journal C 76 (4) (April). doi:10.1140/epjc/s10052-016-4034-8.1434-6044http://nrs.harvard.edu/urn-3:HUL.InstRepos:33839905Results of a search for new phenomena in events with at least three photons are reported. Data from proton–proton collisions at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb −1−1 , were collected with the ATLAS detector at the LHC. The observed data are well described by the Standard Model. Limits at the 95 % confidence level on new phenomena are presented based on the rate of events in an inclusive signal region and a restricted signal region targeting the rare decay Z→3γZ→3γ , as well as di-photon and tri-photon resonance searches. For a Standard Model Higgs boson decaying to four photons via a pair of intermediate pseudoscalar particles (a), limits are found to be σ× BR (h→aa)× BR (a→γγ)2<10−3σSMσ× BR (h→aa)× BR (a→γγ)2<10−3σSM for 10 GeV <ma<<ma< 62 GeV. Limits are also presented for Higgs boson-like scalars (H) for mH>mH> 125 GeV, and for a Z′Z′ decaying to three photons via Z′→a+γ→3γZ′→a+γ→3γ . Additionally, the observed limit on the branching ratio of the Z boson decay to three photons is found to be BR (Z→3γ)<2.2×10−6(Z→3γ)<2.2×10−6 , a result five times stronger than the previous result from LEP.en-USJournal Article2017-09-0610.1140/epjc/s10052-016-4034-8