Measurement of Spin Correlations of Top-Antitop Pairs in the ATLAS Experiment

The aim of our work was to investigate the production of top-antitop pairs and the spin correlations when the top (antitop) quark decays to a b-quark and two leptons (only one lepton is detectable, the neutrino is invisible). Several observables describing spin correlations and the corresponding estimators were studied. The effect of spin correlations was studied in the case of proton-proton collisions at the energy of 14 TeV for the ATLAS detector. A full density matrix was used at the generation level. We can conclude that spin correlations could be observed in the ATLAS experiment.