Search for new phenomena in events with at least three photons collected in pp collisions at √{s} = 8 TeV with the ATLAS detector
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^{-3} σ _{ {SM}} 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.
- Publication:
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European Physical Journal C
- Pub Date:
- April 2016
- DOI:
- 10.1140/epjc/s10052-016-4034-8
- arXiv:
- arXiv:1509.05051
- Bibcode:
- 2016EPJC...76..210A
- Keywords:
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- High Energy Physics - Experiment
- E-Print:
- 20 pages plus author list + cover pages (37 pages total), 5 figures, 5 tables, submitted to EPJC