Abstract
The ATLAS and CMS collaborations have recently released their new analyses of the diphoton searches. We look in detail the consequences of their results deriving strong constraints on models where a scalar resonance s decays into two light pseudoscalars which in turn decay into two pairs of collimated photons, mis-identified with two real photons. In our construction, all mass terms are generated dynamically, and only one pair of vector-like fermions generate couplings which will be probed using the upcoming LHC data. Moreover, we show that a stable dark matter candidate, respecting the cosmological constraints, is naturally affordable in the model.
Highlights
It would be intriguing to compare the current experimental limits with the requirement of having a consistent perturbative theory at least up to some energy scale ΛNP, where a further Ultra-Violet (UV) completion should be invoked
To perform a study of this kind we consider the case in which the SM is extended by a SM gauge singlet complex scalar field Φ charged under a new global U (1) symmetry, which can be interpreted as a Peccei - Quinn symmetry for instance [26]
The pseudoscalar component of Φ is promoted to be a light pseudo Goldstone boson by introducing small explicit violation of this new global symmetry. In this setup a diphoton signal would be originated from pairs of highly collimated photons2, produced by the decay of a pair of light pseudoscalars which in turn are originated by the decay of the scalar component of Φ, resonantly produced in proton-proton collision. The advantage of this construction is that the four-photon, i.e., the effective diphoton, cross-section can more attain larger values since it is controlled by branching fraction (Br) of the decay of the scalar component of Φ into two pseudoscalars, which can be pushed to one
Summary
It would be intriguing to compare the current experimental limits with the requirement of having a consistent perturbative theory at least up to some energy scale ΛNP, where a further Ultra-Violet (UV) completion should be invoked This problem can be reformulated by choosing a priori the scale ΛNP and determining the accessible values of an hypothetical future new detection, as function of the mass of the resonance and the diphoton production cross-section. A similar framework giving collimated photons is the Next-to Minimal Supersymmetric Standard Model (NMSSM) [28,29,30] in which the new scalar and pseudoscalar fields are part of an extended Higgs sector In this scenario a sizable production cross-section is achieved through triangle loop of the SM fermions, at the price of a very definite range of the pseudoscalar mass to avoid an otherwise highly suppressed branching fraction into photons.
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