NNLO+PS Monte Carlo simulation of photon pair production with MiNNLOPS

A bstract We present a NNLO QCD accurate event generator for direct photon pair production at hadron colliders, based on the M i NNLO PS formalism, within the P owheg B ox R es 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 M i NNLO PS 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 P ythia 8, and we compare them with the 13 TeV data from the ATLAS Collaboration.