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

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 angular separation in azimuth between the photon and the jet, the photon-jet invariant mass and the scattering angle in the photon-jet centre-of-mass system. The measurements are compared to tree-level plus parton-shower predictions from Sherpa and Pythia as well as to next-to-leading-order QCD predictions from Jetphox and Sherpa.