Diphoton excess through dark mediators

Journal Article · Tue Jul 12 00:00:00 EDT 2016 · Journal of High Energy Physics (Online)

DOI:https://doi.org/10.1007/JHEP07(2016)063· OSTI ID:1361522

Chen, Chien -Yi ^[1]; Lefebvre, Michel ^[2]; Pospelov, Maxim ^[1]; Zhong, Yi -Ming ^[3]

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1. Univ. of Victoria, Victoria, BC (Canada); Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada)
2. Univ. of Victoria, Victoria, BC (Canada)
3. Stony Brook Univ., Stony Brook, NY (United States)

Preliminary ATLAS and CMS results from the first 13 TeV LHC run have encountered an intriguing excess of events in the diphoton channel around the invariant mass of 750 GeV. We investigate a possibility that the current excess is due to a heavy resonance decaying to light metastable states, which in turn give displaced decays to very highly collimated e⁺e^– pairs. Such decays may pass the photon selection criteria, and successfully mimic the diphoton events, especially at low counts. We investigate two classes of such models, characterized by the following underlying production and decay chains: gg → S → A'A' → (e⁺e^–)(e⁺e^–) and qq¯→ Z' → sa → (e⁺e^–) (e⁺e^–), where at the first step a heavy scalar, S, or vector, Z', resonances are produced that decay to light metastable vectors, A', or (pseudo-)scalars, s and a. Setting the parameters of the models to explain the existing excess, and taking the ATLAS detector geometry into account, we marginalize over the properties of heavy resonances in order to derive the expected lifetimes and couplings of metastable light resonances. In conclusion, we observe that in the case of A', the suggested range of masses and mixing angles ϵ is within reach of several new-generation intensity frontier experiments.

• Research Organization: SUNY Stony Brook, Stony Brook, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: SC0008061
• OSTI ID: 1361522
• Journal Information: Journal of High Energy Physics (Online), Vol. 2016, Issue 7; ISSN 1029-8479
• Publisher: Springer Berlin
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Beyond Standard Model
Higgs physics