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

Abstract

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 <math><msubsup is="true"><mrow is="true"><mi is="true">σ</mi></mrow><mrow is="true"><mi mathvariant="normal" is="true">EW</mi></mrow><mrow is="true"><mi is="true">Z</mi><mi is="true">j</mi><mi is="true">j</mi></mrow></msubsup></math> = 119 ± 16 (stat.) ± 20 (syst.)±2 (lumi.) fb for dijet invariant mass greater than 250 GeV, and 34.2±5.8 (stat.)±5.5 (syst.)± 0.7 (lumi.) 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.