Goldstones in Diphotons

TL;DR

This paper investigates the conditions under which a new scalar resonance, potentially observable in diphoton channels at the LHC, can be explained as a Goldstone boson or related scalar, analyzing recent experimental excesses and theoretical models.

Contribution

It identifies two natural candidates for the diphoton resonance as Goldstone bosons or sgoldstinos, and assesses their compatibility with experimental data and theoretical frameworks.

Findings

Goldstone boson from internal symmetry with anomalies is a viable candidate.

Sgoldstino from supersymmetry breaking is also a plausible explanation.

Dilaton from conformal symmetry breaking is disfavoured by current data.

Abstract

We study the conditions for a new 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 and composite Higgs models. We show that two candidates naturally emerge: a Goldstone boson from an internal symmetry with electromagnetic anomalies, and the scalar partner of the Goldstone of supersymmetry breaking: the sgoldstino. The dilaton from conformal symmetry breaking is instead disfavoured by present data, in its minimal natural realization.