This process is calculable at leading order LO. This process represents the production of a lepton pair through an electroweak process involving two photons in the initial state, γγ → e-e+. Since the reaction has initial photons, it is important to have an accurate parton distribution function for the photon in the proton, e.g. LUXqed17_plus_PDF4LHC15_nnlo_30.
nplotter_Z_only.f is the default plotting routine.