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

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${}_{\mathrm{PS}}$ 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 $2\to 2$ 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.

Comments: 42 pages, 10 figures, 2 tables