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

TL;DR

This paper introduces a NNLO+PS Monte Carlo event generator for photon pair production at hadron colliders, enabling precise simulations with arbitrary cuts and improved scale setting, validated against ATLAS data.

Contribution

It presents a novel NNLO accurate event generator based on MiNNLOPS within the POWHEG framework, with modifications for better scale setting and no need for technical cuts.

Findings

Accurate simulation of photon pair production at NNLO+PS level.

Good agreement with 13 TeV ATLAS data.

Flexible kinematic distributions with arbitrary fiducial cuts.

Abstract

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.