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

  • Author(s): Aad, G
  • Abbott, B
  • Abdallah, J
  • Abdinov, O
  • Aben, R
  • Abolins, M
  • Abouzeid, OS
  • Abramowicz, H
  • Abreu, H
  • Abreu, R
  • Abulaiti, Y
  • Acharya, BS
  • Adamczyk, L
  • Adams, DL
  • Adelman, J
  • Adomeit, S
  • Adye, T
  • Affolder, AA
  • Agatonovic-Jovin, T
  • Agricola, J
  • Aguilar-Saavedra, JA
  • Ahlen, SP
  • Ahmadov, F
  • Aielli, G
  • Akerstedt, H
  • Åkesson, TPA
  • Akimov, AV
  • Alberghi, GL
  • Albert, J
  • Albrand, S
  • Alconada Verzini, MJ
  • Aleksa, M
  • Aleksandrov, IN
  • Alexa, C
  • Alexander, G
  • Alexopoulos, T
  • Alhroob, M
  • Alimonti, G
  • Alio, L
  • Alison, J
  • Alkire, SP
  • Allbrooke, BMM
  • Allport, PP
  • Aloisio, A
  • Alonso, A
  • Alonso, F
  • Alpigiani, C
  • Altheimer, A
  • Alvarez Gonzalez, B
  • Álvarez Piqueras, D
  • Alviggi, MG
  • Amadio, BT
  • Amako, K
  • Amaral Coutinho, Y
  • Amelung, C
  • Amidei, D
  • Amor Dos Santos, SP
  • Amorim, A
  • Amoroso, S
  • Amram, N
  • Amundsen, G
  • Anastopoulos, C
  • Ancu, LS
  • Andari, N
  • Andeen, T
  • Anders, CF
  • Anders, G
  • Anders, JK
  • Anderson, KJ
  • Andreazza, A
  • Andrei, V
  • Angelidakis, S
  • Angelozzi, I
  • Anger, P
  • Angerami, A
  • Anghinolfi, F
  • Anisenkov, AV
  • Anjos, N
  • Annovi, A
  • Antonelli, M
  • Antonov, A
  • Antos, J
  • Anulli, F
  • Aoki, M
  • et al.
Abstract

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

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