750 GeV Diphoton excess from $E_6$ in F-theory GUTs

We interpret the 750-760 GeV diphoton resonance as one or more of the spinless components of a singlet superfield arising from the three 27-dimensional representations of $E_6$ in F-theory, which also contain three copies of colour-triplet charge $\mp 1/3$ vector-like fermions $D_i,\bar{D}_i$ and inert Higgs doublets to which the singlets may couple. For definiteness we consider (without change) a model that was proposed some time ago which contains such states, as well as bulk exotics, leading to gauge coupling unification. The smoking gun prediction of the model is the existence of other similar spinless resonances, possibly close in mass to 750-760 GeV, decaying into diphotons, as well as the three families of vector-like fermions $D_i,\bar{D}_i$.