Speaker
Description
The production of jets and prompt isolated photons at hadron colliders provides stringent tests of perturbative QCD. The most recent measurements in this area by the ATLAS experiment, using proton-proton collision data at $\sqrt{s}$ =13 TeV, are presented. Prompt inclusive photon production is measured for two distinct photon isolation cones, R=0.2 and 0.4, as well as for their ratio. The measurement is sensitive to gluon parton density distribution. Various measurements of event shapes in multijet events are presented, as well. The talk will discuss measurements of new event-shape jet observables defined in terms of reference geometries with cylindrical and circular symmetries using the energy mover???s distance, as well as variables probing the properties of the multijet energy flow. The latter are also used to determine the strong coupling constant. The measurements are compared to state-of-the-art theory predictions from a range of parton shower programs and fixed order calculations. Furthermore, measurements of jets in association with an electroweak gauge boson are highlighted. The differential measurement of W boson production in association with charm D+ and D*+ vector mesons will be discussed and compared to QCD calculations including NNLO parton distribution functions and constraints on parton distribution functions. Recent results of Z+jets production using new machine-learning techniques to extract multi-differential cross sections will be presented. The measurements are compared to state-of-the-art theory predictions.
