NNLO QCD corrections to diphoton production with an additional jet at the LHC

TL;DR

This paper delivers the first NNLO QCD prediction for diphoton production with an additional jet at the LHC, yielding a NNLO-accurate $p_T(\gamma\gamma)$ spectrum that significantly reduces scale uncertainties relative to NLO. It employs the STRIPPER framework with exact IR structure and a leading-color approximation for the two-loop finite remainder, supplemented by the loop-induced $gg\to g\gamma\gamma$ contribution, which is important at low $p_T$. The results demonstrate substantial improvements in perturbative stability for key observables and provide detailed differential distributions, including two-dimensional ones, at 13 TeV with realistic photon isolation and cuts. The work lays groundwork toward higher-order refinements (partial N3LO corrections, resummation) and supports precise background estimates for Higgs and diphoton-resonance studies.

Abstract

We calculate the NNLO QCD corrections to diphoton production with an additional jet at the LHC. Our calculation represents the first NNLO-accurate prediction for the transverse momentum distribution of the diphoton system. The improvement in the accuracy of the theoretical prediction is significant, by a factor of up to four relative to NLO QCD. Our calculation is exact except for the finite remainder of the two-loop amplitude which is included at leading color. The numerical impact of this approximated contribution is small. The results of this work are expected to further our understanding of the Higgs boson sector and of the behavior of higher-order corrections to LHC processes.

Figures (7)

• Figure 1: Absolute ${p_T(\gamma\gamma)}$ (left) and $m(\gamma\gamma)$ (right) differential distributions. Shown are the predictions in LO (green), NLO (blue), NNLO (red) QCD. The colored bands around the central scales are from 7-point scale variation. The grey band shows the estimated Monte Carlo integration error in each bin. The lower panel shows the same distributions but relative to the NLO central scale prediction.
• Figure 2: As in fig. \ref{['fig:PT-m']} but for the $m(\gamma\gamma)$ distribution subjected to different ${p_T(\gamma\gamma)}$ cuts: ${p_T(\gamma\gamma)}>50$ GeV (left), ${p_T(\gamma\gamma)}>100$ GeV (center) and ${p_T(\gamma\gamma)}>200$ GeV (right).
• Figure 3: As in fig. \ref{['fig:PT-m']} but for the angular distributions in $\phi_{CS}$ (left) and $\Delta\phi(\gamma\gamma)$ (right).
• Figure 4: As in fig. \ref{['fig:PT-m']} but for the following rapidity distributions: $\Delta y(\gamma\gamma)$ (left) and $|y(\gamma\gamma)|$ (right).
• Figure 5: Two-dimensional differential distributions: in $\phi_{CS} \otimes m(\gamma\gamma)$ (left) and in $m(\gamma\gamma)\otimes p_T(\gamma\gamma)$ but shown in two alternative forms and for different choice of bins: in ${p_T(\gamma\gamma)}$ bins (center) and with ${p_T(\gamma\gamma)}$ cuts (right). Only the NLO and NNLO central scale predictions and scale variation bands are shown. Note that the figure to the right shows the same results that already appear in figs. \ref{['fig:PT-m']},\ref{['fig:m-cuts']}.