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

Summary, in English

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. © CERN for the benefit of the ATLAS collaboration 2016.

• Author: G Aad; B. Abbott; J. Abdallah; O Abdinov; R Aben; M Abolins; Torsten Åkesson; Simona Bocchetta; Lene Bryngemark; Caterina Doglioni; Anders Floderus; Anthony Hawkins; Vincent Hedberg; Jenny Ivarsson; Göran Jarlskog; Else Lytken; Ulf Mjörnmark; Oxana Smirnova; Oleksandr Viazlo
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration
• Publishing year: 2016
• Language: English
• Publication/Series: European Physical Journal C
• Volume: 76
• Issue: 4
• Links: http://dx.doi.org/10.1140/epjc/s10052-016-4034-8
• Document type: Journal article
• Publisher: Springer
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1434-6044