Hadroproduction of t-anti-t pair with two isolated photons with PowHel

We simulate the hadroproduction of a t (t) over bar 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 (t) over bar H final state when the Higgs-boson decays into a photon pair, to which the process discussed here is an irreducible background. (C) 2015 The Authors. Published by Elsevier B.V.