The 750 GeV diphoton resonance as a singlet scalar in an extra dimensional model

We interpret the 750~GeV diphoton excess recently found in the 13~TeV LHC data as a singlet scalar in an extra dimensional model, where one extra dimension is introduced. In the model, the scalar couples to multiple vector-like fermions, which are just the KK modes of SM fermions. Mediated by the loops of these vector-like fermions, the $\varphi$ effective couplings to gluons and photons can be significantly large. Therefore, it is quite easy to obtain an observed cross section for the diphoton excess. We also calculate the cross sections for other decay channels of $\varphi$, and find that this interpretation can evade the bounds from the 8~TeV LHC data.