Features in the Standard Model diphoton background
  We argue that electromagnetic decays of energetic unflavoured neutral mesons, notably $\eta$, mis-identified as single photons due to granularity of the electromagnetic calorimeter might create bump-like features in the diphoton invariant mass spectrum at different energies, including 750 GeV. We discuss what kind of additional analysis can exclude or confirm this hypothesis. 
Kyrylo Bondarenko, Alexey Boyarsky, Oleg Ruchayskiy, Mikhail   Shaposhnikov
hep-ph hep-ex