The diphoton excess around $m_X=750\mathrm{GeV}$ observed by ATLAS and CMS can be interpreted as coming from a massive spin-2 excitation. We explore this possibility in the context of warped five-dimensional models with the Standard Model (SM) fields propagating in the bulk of the extra dimension. The 750 GeV resonance is identified with the first Kaluza-Klein (KK) excitation of the five-dimensional graviton that is parametrically lighter than KK resonances of SM fields. Our setup makes it possible to realize nonuniversal couplings of the spin-2 resonance to matter, and thus to explain nonobservation of the 750 GeV resonance in leptonic channels. Phenomenological predictions of the model depend on the localization of fields in the extra dimension. If, as required by naturalness arguments, the zero modes of the Higgs and top fields are localized near the IR brane, one expects large branching fractions to $t\overline{t}$, $hh$, $W^{+}{W}^{-}$ and $ZZ$ final states. Decays to $Z\gamma$ can also be observable when the KK graviton couplings to the SM gauge fields are nonuniversal.

• Received 11 May 2016

DOI:https://doi.org/10.1103/PhysRevD.94.015008