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 -> 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 xBR( h -> aa) xBR(a -> gamma gamma) 2 < 10(-3) sigma(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' -> a + gamma -> 3 gamma. Additionally, the observed limit on the branching ratio of the Z boson decay to three photons is found to be BR( Z -> 3 gamma) < 2.2 x 10(-6), a result five times stronger than the previous result from LEP.

Search for new phenomena in events with at least three photons collected in pp collisions at root s=8 TeV with the ATLAS detector / Iuppa, R; Atlas, Collaboration. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 76:4(2016), pp. 21001-21026. [10.1140/epjc/s10052-016-4034-8]

Search for new phenomena in events with at least three photons collected in pp collisions at root s=8 TeV with the ATLAS detector

Iuppa, R;
2016

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 -> 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 xBR( h -> aa) xBR(a -> gamma gamma) 2 < 10(-3) sigma(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' -> a + gamma -> 3 gamma. Additionally, the observed limit on the branching ratio of the Z boson decay to three photons is found to be BR( Z -> 3 gamma) < 2.2 x 10(-6), a result five times stronger than the previous result from LEP.
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Iuppa, R; Atlas, Collaboration
Search for new phenomena in events with at least three photons collected in pp collisions at root s=8 TeV with the ATLAS detector / Iuppa, R; Atlas, Collaboration. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 76:4(2016), pp. 21001-21026. [10.1140/epjc/s10052-016-4034-8]
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11572/162899
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