Measurement of the cross section for isolated-photon plus jet production in $pp$ collisions at $\sqrt s=13$ TeV using the ATLAS detector

TL;DR

This paper reports measurements of the cross sections for isolated-photon plus jet production in proton-proton collisions at 13 TeV using the ATLAS detector, comparing results with various theoretical predictions to test QCD models.

Contribution

First measurement of isolated-photon plus jet cross sections at 13 TeV with detailed comparison to QCD predictions.

Findings

Measured cross sections as functions of photon and jet kinematics.

Good agreement with NLO QCD predictions within uncertainties.

Provides data for testing and refining QCD models.

Abstract

The dynamics of isolated-photon production in association with a jet in proton-proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb$^{-1}$. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti-$k_t$ algorithm with radius parameter $R=0.4$ and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon-jet invariant mass and the scattering angle in the photon-jet centre-of-mass system. Tree-level plus parton-shower predictions from SHERPA and PYTHIA as well as next-to-leading-order QCD predictions from JETPHOX and SHERPA are compared to the measurements.