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 → 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 → γ γ)2< 10−3σSM for 10 GeV < ma < 62 GeV. Limits are also presented for Higgs boson-like scalars (H) for mH > 125 GeV, and for a Z' decaying to three photons via Z' → 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, 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 √s = 8 TeV with the ATLAS detector

CAVASINNI, VINCENZO;DELL'ORSO, MAURO;DONATI, SIMONE;Francavilla, P.;RODA, CHIARA MARIA ANGELA;Verducci, M.;
2016-01-01

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 → 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 → γ γ)2< 10−3σSM for 10 GeV < ma < 62 GeV. Limits are also presented for Higgs boson-like scalars (H) for mH > 125 GeV, and for a Z' decaying to three photons via Z' → 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, a result five times stronger than the previous result from LEP.
2016
Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; Abouzeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/826164
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