Stable perturbative predictions for isolated photon production with a jet pair at large $m_{j_1 j_2}$

TL;DR

The paper addresses perturbative instabilities in fixed-order predictions for isolated photon production with two jets at large dijet invariant mass $m_{j_1 j_2}$. It introduces High Energy Jets (HEJ) resummation to all orders, capturing high-energy logarithms $\alpha_s^k \log(s/t)$ and matching to NLO to stabilize the $d\sigma/dm_{j_1 j_2}$ distribution. The combined QCD+EW predictions describe ATLAS 13 TeV data well, with HEJ significantly improving the shape description compared to fixed-order approaches, suggesting that high-energy logarithms are crucial in this phase space. The results underscore the importance of resummation for accurate, model-independent predictions in jet-vetoed, high-energy topologies and guide future studies in related vector-boson plus jets channels.

Abstract

We present the first calculation of the high-energy corrections to the process of isolated photon production in association with two jets. These corrections both stabilise the perturbative behaviour in $m_{j_1j_2}$ and lead to a significantly improved description of data from a recent ATLAS measurement.

Figures (13)

• Figure 1: $\mathrm{d}\xspace\sigma/\mathrm{d}\xspace m_{j_1 j_2}\xspace$ for LO and NLO for $pp\to \gamma jj$($\alpha_s\xspace^2 \alpha$) with central scale choice $\mu_R=\mu_F=\hat{H}_T/2\xspace$ and a standard 7-point scale variation.
• Figure 2: $\mathrm{d}\xspace\sigma/\mathrm{d}\xspace m_{j_1 j_2}\xspace$ for pure QCD LO, NLO and HEJ matched to NLO
• Figure 3: $\mathrm{d}\xspace\sigma/\mathrm{d}\xspace m_{j_1 j_2}\xspace$ for the QCD component (calculated with HEJ) and the electro-weak component (calculated with VBFNLO). The process is dominated by the QCD contribution until around 3TeV.
• Figure 4: $\mathrm{d}\xspace\sigma/\mathrm{d}\xspace m_{j_1 j_2}\xspace$ for NLO QCD+EW(VBFNLO), HEJ+EW(VBFNLO) and data. The prediction for HEJ is matched to NLO.
• Figure 5: $\mathrm{d}\xspace\sigma/\mathrm{d}\xspace m_{j_1 j_2}\xspace$ for scaled NLO, HEJ and data, see table \ref{['tab:chi2']} for the scaling factors and $\chi^2/\mathrm{dof}$ obtained.