Interpreting a 750 GeV Diphoton Resonance

Abstract

We discuss the implications of the significant excesses in the diphoton final state observed by the LHC experiments ATLAS and CMS around a diphoton invariant mass of 750 GeV. The interpretation of the excess as a spin-zero s-channel resonance implies model-independent lower bounds on both its branching ratio and its coupling to photons, which stringently constrain dynamical models. We consider both the case where the excess is described by a narrow and a broad resonance. We also obtain model-independent constraints on the allowed couplings and branching fractions to final states other than diphotons, by including the interplay with 8 TeV searches. These results can guide attempts to construct viable dynamical models of the resonance. Turning to specific models, our findings suggest that the anomaly cannot be accounted for by the presence of only an additional singlet or doublet spin-zero field and the Standard Model degrees of freedom; this includes all two-Higgs-doublet models. Likewise, heavy scalars in the MSSM cannot explain the excess if stability of the electroweak vacuum is required, at least in a leading-order analysis. If we assume that the resonance is broad we find that it is challenging to find a weakly coupled explanation. However, we provide an existence proof in the form of a model with vectorlike quarks with large electric charge that is perturbative up to the 100 TeV scale. For the narrow-resonance case a similar model can be perturbative up to high scales also with smaller charges. We also find that, in their simplest form, dilaton models cannot explain the size of the excess. Some implications for flavor physics are briefly discussed.

36 pages, 7 figures. v4: added electroweak-boson initial states, including with photons; minor improvements of presentation; published version

References in corpus (25)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• Light scalar at LHC: the Higgs or the dilaton?
• Search for high-mass dilepton resonances in pp collisions at sqrt(s) = 8 TeV with the ATLAS detector
• Status of the Higgs Singlet Extension of the Standard Model after LHC Run 1
• Beyond the Minimal Composite Higgs Model
• What is the gamma gamma resonance at 750 GeV?
• Composite Models for the 750 GeV Diphoton Excess
• Scenarii for interpretations of the LHC diphoton excess: two Higgs doublets and vector-like quarks and leptons
• On the Interpretation of a Possible $\sim 750$ GeV Particle Decaying into $\gamma \gamma$
• Search for narrow resonances decaying to dijets in proton-proton collisions at sqrt(s) = 13 TeV
• Search for New Phenomena in Dijet Mass and Angular Distributions from $pp$ Collisions at $\sqrt{s}$ = 13 TeV with the ATLAS Detector
• The LHC diphoton resonance and dark matter
• The QCD Axion from Aligned Axions and Diphoton Excess
• Di-photon excess illuminates Dark Matter
• A pseudoscalar decaying to photon pairs in the early LHC Run 2 data
• Footprints of New Strong Dynamics via Anomaly and the 750 GeV Diphoton
• Singlet Scalar Resonances and the Diphoton Excess
• Knocking on New Physics' door with a Scalar Resonance
• The 750 GeV diphoton excess from the goldstino superpartner
• Indirect Probes of the MSSM after the Higgs Discovery
• Stabilizing Electroweak Vacuum in a Vector-like Fermion Model
• The production of a diphoton resonance via photon-photon fusion
• Goldstones in Diphotons
• Fermion Hierarchy from Sfermion Anarchy
• A new scalar resonance at 750 GeV: Towards a proof of concept in favor of strongly interacting theories

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• Implications of a High-Mass Diphoton Resonance for Heavy Quark Searches
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• Di-Photon excess in the 2HDM: hasting towards the instability and the non-perturbative regime
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• A Dark Sector for $g_{\mu }-2$, $R_K$ and a Diphoton Resonance
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• Learning from the New Higgs-like Scalar before It Vanishes
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• Minimal Dilaton Model and the Diphoton Excess
• Astrophysical Constraints on Singlet Scalars at LHC
• Phenomenology of an $SU(2{)}_1\times SU(2{)}_2\times U(1{)}_Y$ model at the LHC
• Diphoton and Dark Matter from Cascade Decay
• Loop induced singlet scalar production through the vector like top quark at future lepton colliders