The LHC diphoton resonance from gauge symmetry

Abstract

Motivated by what is possibly the first sign of new physics seen at the LHC, the diphoton excess at $750$ GeV in ATLAS and CMS, we present a model that provides naturally the necessary ingredients to explain the resonance. The simplest phenomenological explanation for the diphoton excess requires a new scalar state, $X(750)$, as well as additional vector-like (VL) fermions introduced in an ad-hoc way in order to enhance its decays into a pair of photons and/or increase its production cross-section. We show that the requiered VL quarks and their couplings can emerge naturally from a complete framework based on the $SU(3{)}_L\otimes U(1{)}_{\mathcal{X}}$ gauge symmetry.

Comments: 8 pages; 2 figures. v2: new references. v3: matches published version in PRD