Photo-production of a 750 GeV di-photon resonance mediated by Kaluza-Klein leptons in the loop

We consider the phenomenology of a 750 gev resonance x which can be produced at the lhc by only photon fusion and subsequently decay into di-photons. we propose that the spin-zero state x is coupled to a heavy lepton that lives in the bulk of a higher-dimensional theory and interacts only with the photons of the standard model. we compute the di-photon rate in these models with two and more compact extra dimensions and demonstrate that they allow for a compelling explanation of the di-photon excess recently observed by the atlas and cms collaborations. the central role in our approach is played by the summation over the kaluza-klein modes of the new leptons, thus providing a significant enhancement of the x → γγ loops for the production and decay subprocesses. it is expected that the jet activity accompanying these purely electromagnetic (at the partonic level) processes is numerically suppressed by factors such as $$ {alpha}_{mathrm{em}}^2{mathcal{c}}_{qoverline{q}}/{mathcal{c}}_{gamma gamma}sim 1{0}^{-3} $$ .