ATLAS collaboration (2926 authors)Aguilar-Saavedra, Juan AntonioAmor Dos Santos, Susana PatriciaAnjos, NunoCantrill, RobertCarvalho, JoãoCastro, Nuno FilipeConde Muiño, PatriciaDa Cunha Sargedas De Sousa, Mario JoseDo Valle Wemans, AndréFiolhais, MiguelGalhardo, BrunoGomes, AgostinhoGonçalo, RicardoJorge, PedroLopes, LourencoMachado Miguens, JoanaMaio, AméliaManeira, JoséMarques, CarlosOliveira, Miguel AlfonsoOnofre, AntónioPalma, AlbertoPina, João AntonioPinto, BelmiroSantos, HelenaSaraiva, JoãoSilva, JoséTavares Delgado, AdemarVeloso, FilipeWolters, Helmut2019-02-032019-02-032013-12-04http://dx.doi.org/10.1103/PhysRevLett.111.232002http://hdl.handle.net/10400.26/26454This Letter presents measurements of the polarization of the top quark in top–antitop quark pair events, using 4.7 fb$^{¯1}$ of proton–proton collision data recorded with the ATLAS detector at the Large Hadron Collider at √s = 7 TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered. Two measurements of $\alpha_l P$, the product of the leptonic spin-analyzing power and the top quark polarization, are performed assuming that the polarization is introduced by either a CP conserving (CPC) or a CP violating (CPV) production process. The measurements obtained, $\alpha_l P_{CPC} = −0.035± 0.014(stat) ± 0.037(syst)$ and $\alpha_l P_{CPV} = 0.020 ± 0.016(stat)^{+0.013} _{-0.017}(syst)$, are in good agreement with the Standard Model prediction of negligible top quark polarization.engjournal article2019-02-03