Measurement of spin correlations of top-antitop pairs in the ATLAS experiment and influence of heavy Higgs boson

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. 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 also investigated the influence of heavy Higgs boson on spin correlations. We can conclude that spin correlations could be observed in the ATLAS experiment and the ATLAS detector enable the study of the dynamics of heavy quark production and decay. (8 refs).