Hadroproduction of t anti-t pair with two isolated photons with PowHel
  We simulate the hadroproduction of a t anti-t pair in association with two isolated hard photons at 13 TeV LHC using the PowHel package. We use the generated events, stored according to the Les-Houches event format, to make predictions for differential distributions formally at the next-to-leading order (NLO) accuracy. We present predictions at the hadron level employing the cone-type isolation of the photons used by experiments. We also compare the kinematic distributions to the same distributions obtained in the t anti-t H final state when the Higgs-boson decays into a photon pair, to which the process discussed here is an irreducible background. 
Adam Kardos and Zolt\'an Tr\'ocs\'anyi
hep-ph