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Title
Japanese:Search for new phenomena in events with at least three photons collected in $pp$ collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector 
English:Search for new phenomena in events with at least three photons collected in $pp$ collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector 
Author
Japanese: 山口洋平.  
English: Youhei Yamaguchi.  
Language English 
Journal/Book name
Japanese: 
English: 
Volume, Number, Page Vol. "C76"    No. "4"    pp. "210"
Published date Sept. 2015 
Publisher
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English: 
Conference name
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English: 
Conference site
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English: 
Official URL http://inspirehep.net/record/1393757
 
DOI https://doi.org/10.1140/epjc/s10052-016-4034-8
Abstract Results 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$^{-1}$ , 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\rightarrow 3\gamma $ , 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 $\sigma \times {\text{ BR }}(h \rightarrow aa) \times {\text{ BR }}(a \rightarrow \gamma \gamma )^{2} < 10^{-3} \sigma _{\text {SM}}$ for 10 GeV $< m_{a} <$ 62 GeV. Limits are also presented for Higgs boson-like scalars (H) for $m_{H} > $ 125 GeV, and for a $Z'$ decaying to three photons via $Z' \rightarrow a+\gamma \rightarrow 3\gamma $ . Additionally, the observed limit on the branching ratio of the Z boson decay to three photons is found to be BR $(Z \rightarrow 3\gamma ) < 2.2 \times 10^{-6}$ , a result five times stronger than the previous result from

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