Goldstones in Diphotons

We study the conditions for a new sub-TeV scalar resonance to be observed first in diphotons at the LHC Run-2. We focus on scenarios where the scalar arises either from an internal or spacetime symmetry broken spontaneously, for which the mass is naturally below the cutoff and the low-energy interactions are fixed by the couplings to the broken currents, UV anomalies, and selection rules. We discuss the recent excess in diphoton resonance searches observed by ATLAS and CMS at 750 GeV, and explore its compatibility with other searches at Run-1 and its interpretation as Goldstone bosons in supersymmetry, composite Higgs models, and dilaton models. We show that two candidates naturally emerge: a CP-odd Goldstone boson from an internal symmetry with electromagnetic and colour anomalies, and the CP-even scalar partner of the Goldstone of supersymetry breaking: the sgoldstino. The dilaton from breaking conformal symmetry is instead disfavoured by present data.