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Title: Diphoton excess through dark mediators

Abstract

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 rangemore » of masses and mixing angles ϵ is within reach of several new-generation intensity frontier experiments.« less

Authors:
 [1];  [2];  [1];  [3]
  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)
Publication Date:
Research Org.:
SUNY Stony Brook, Stony Brook, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1361522
Grant/Contract Number:
SC0008061
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2016; Journal Issue: 7; Journal ID: ISSN 1029-8479
Publisher:
Springer Berlin
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Beyond Standard Model; Higgs physics

Citation Formats

Chen, Chien -Yi, Lefebvre, Michel, Pospelov, Maxim, and Zhong, Yi -Ming. Diphoton excess through dark mediators. United States: N. p., 2016. Web. doi:10.1007/JHEP07(2016)063.
Chen, Chien -Yi, Lefebvre, Michel, Pospelov, Maxim, & Zhong, Yi -Ming. Diphoton excess through dark mediators. United States. doi:10.1007/JHEP07(2016)063.
Chen, Chien -Yi, Lefebvre, Michel, Pospelov, Maxim, and Zhong, Yi -Ming. 2016. "Diphoton excess through dark mediators". United States. doi:10.1007/JHEP07(2016)063. https://www.osti.gov/servlets/purl/1361522.
@article{osti_1361522,
title = {Diphoton excess through dark mediators},
author = {Chen, Chien -Yi and Lefebvre, Michel and Pospelov, Maxim and Zhong, Yi -Ming},
abstractNote = {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.},
doi = {10.1007/JHEP07(2016)063},
journal = {Journal of High Energy Physics (Online)},
number = 7,
volume = 2016,
place = {United States},
year = 2016,
month = 7
}

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Cited by: 2works
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  • The existence of dark matter (DM) and the origin of the baryon asymmetry are persistent indications that the SM is incomplete. More recently, the ATLAS and CMS experiments have observed an excess of diphoton events with invariant mass of about 750 GeV. One interpretation of this excess is decays of a new spin-0 particle with a sizable diphoton partial width, e.g. induced by new heavy weakly charged particles. These are also key ingredients in models cogenerating asymmetric DM and baryons via sphaleron interactions and an initial particle asymmetry. We explore what consequences the new scalar may have for models ofmore » asymmetric DM that attempt to account for the similarity of the dark and visible matter abundances.« less
  • We present a simple extension of the Standard Model (SM) to explain the recent diphoton excess, reported by CMS and ATLAS at CERN LHC. The SM is extended by a dark sector including a vector-like lepton doublet and a singlet of zero electromagnetic charge, which are odd under a Z{sub 2} symmetry. The charged particle of the vector-like lepton doublet assist the additional scalar, different from SM Higgs, to decay to di-photons of invariant mass around 750 GeV and thus explaining the excess observed at LHC. The admixture of neutral component of the vector-like lepton doublet and singlet constitute themore » dark matter of the Universe. We show the relevant parameter space for correct relic density and direct detection of dark matter.« less
  • We investigate a simple setup in which an excess in the di-photon invariant mass distribution around 750 GeV, as seen by the ATLAS and CMS collaborations, is originated through a pair of collimated photon pairs. In this framework a scalar state s decays into two light pseudo-Goldstone bosons a, each of which subsequently decays into a pair of collimated photons which are misidentified as a single photon. In a minimal context of spontaneous symmetry breaking, we show that coupling a complex scalar field Φ=(s+ia)/√2 to a fermionic dark matter candidate χ, also responsible for generating its mass, allows for themore » correct relic density in a large region of the parameter space, while not being excluded by the direct or indirect detection experiments. Moreover, the correct relic abundance can naturally co-exist with a relatively large width for the resonant field s.« less
  • Cited by 18