Measurement of the ZZ production cross section in Run 2 of the LHC with the ATLAS experiment. Acceptance determination

The study of Z boson pair production in proton-proton interactions tests the predictions of the electroweak sector of the Standard Model (SM), and this process is also an important background in Higgs analyses. Furthermore the production of new resonances decaying to pairs of Z bosons, as well as non-zero neutral triple gauge boson couplings could lead to deviations from the SM prediction. For the measurement of the cross section for ZZ production the decay channel ZZ → l⁺l^-l^'+l^'- was analyzed, where l resp. l^' denote an electron, or a muon. For this analysis data from proton-proton collisions at the LHC, located at CERN, were used to measure the cross section in a fiducial region. These data were recorded with the ATLAS experiment at √(s) = 13 TeV with an integrated luminosity of 3.2 fb^-1. In order to extrapolate this fiducial cross section to an on-shell phase space a so called acceptance factor needs to be determined. In this talk the acceptance with its systematic uncertainties is presented in a detailed way, and the resulting total cross section are shown.