Measurement of the cross-section for electroweak production of dijets in association with a Z boson in pp collisions at √s̅ = 13 TeV with the ATLAS detector

The cross-section for the production of two jets in association with a leptonically decaying Z boson (Zjj ) is measured in proton–proton collisions at a centre-of-mass energy of 13 TeV, using data recorded with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 3.2 fb⁻¹. The electroweak Zjj cross-section is extracted in a fiducial region chosen to enhance the electroweak contribution relative to the dominant Drell–Yan Zjj process, which is constrained using a data-driven approach. The measured fiducial electroweak cross-section is σ ^Zjj_EW = 119 ± 16 (stat.) ± 20 (syst.) ± 2 (lumni.) fb for dijet invariant mass greater than 250 GeV, and 34.2 ± 5.8 (stat.) ± 5.5 (syst.) ± 0.7 (lumni) fb for dijet invariant mass greater than 1 TeV. Standard Model predictions are in agreement with the measurements. The inclusive Zjj cross-section is also measured in six different fiducial regions with varying contributions from electroweak and Drell–Yan Zjj production.