  We present a NNLO QCD accurate event generator for direct photon pair
production at hadron colliders, based on the MiNNLOPS formalism, within the
POWHEG BOX RES framework. Despite the presence of the photons requires the use
of isolation criteria, our generator is built such that no technical cuts are
needed at any stage of the event generation. Therefore, our predictions can be
used to simulate kinematic distributions with arbitrary fiducial cuts.
Furthermore, we describe a few modifications of the MiNNLOPS formalism in order
to allow for a setting of the renormalization and factorization scales more
similar to that of a fixed-order computation, thus reducing the numerical
impact of higher-order terms beyond the nominal accuracy. Finally, we show
several phenomenological distributions of physical interest obtained by
showering the generated events with Pythia8, and we compare them with the 13
TeV data from the ATLAS Collaboration.
