Advancing MiNNLO$_{\rm PS}$ to diboson processes: $Z\gamma$ production at NNLO+PS

TL;DR

This paper extends the MiNNLO$_{ m PS}$ method to $Z o ext{dilepton}+ ext{photon}$ production at NNLO+PS accuracy, including full effects, and demonstrates its importance for precise LHC predictions in agreement with data.

Contribution

It presents the first NNLO+PS calculation for $Z o ext{dilepton}+ ext{photon}$ production without requiring reweighting, advancing the simulation of diboson processes at the LHC.

Findings

NNLO corrections significantly improve accuracy.

Matching to parton showers is essential.

Predictions agree well with ATLAS data.

Abstract

We consider $Z \gamma$ production in hadronic collisions and present the first computation of next-to-next-to-leading order accurate predictions consistently matched to parton showers (NNLO+PS). Spin correlations, interferences and off-shell effects are included by calculating the full process $pp\to\ell^+\ell^-\gamma$. We extend the recently developed MiNNLO$_{\rm PS}$ method to genuine $2\to 2$ hard scattering processes at the LHC, which paves the way for NNLO+PS simulations of all diboson processes. This is the first $2\to2$ NNLO+PS calculation that does not require an a-posteriori multi-differential reweighting. We find that both NNLO corrections and matching to parton showers are crucial for an accurate simulation of the $Z \gamma$ process. Our predictions are in very good agreement with recent ATLAS data.