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      Search for new phenomena in events with at least three photons collected in pp collisions at \(\sqrt{s}\) = 8 TeV with the ATLAS detector

      The European Physical Journal. C, Particles and Fields

      Springer

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          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 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document} - 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 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Z\rightarrow 3\gamma $$\end{document} Z → 3 γ , 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 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma \times {\text{ BR }}(h \rightarrow aa) \times {\text{ BR }}(a \rightarrow \gamma \gamma )^{2} < 10^{-3} \sigma _{\text {SM}}$$\end{document} σ × BR ( h → a a ) × BR ( a → γ γ ) 2 < 10 - 3 σ SM for 10 GeV \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$< m_{a}<$$\end{document} < m a < 62 GeV. Limits are also presented for Higgs boson-like scalars (H) for \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$m_{H} > $$\end{document} m H > 125 GeV, and for a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Z'$$\end{document} Z ′ decaying to three photons via \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Z' \rightarrow a+\gamma \rightarrow 3\gamma $$\end{document} Z ′ → a + γ → 3 γ . Additionally, the observed limit on the branching ratio of the Z boson decay to three photons is found to be BR \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(Z \rightarrow 3\gamma ) < 2.2 \times 10^{-6}$$\end{document} ( Z → 3 γ ) < 2.2 × 10 - 6 , a result five times stronger than the previous result from LEP.

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                Author and article information

                Journal
                5312246
                10.1140/epjc/s10052-016-4034-8
                1509.05051

                http://creativecommons.org/licenses/by/4.0/

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