ATLAS collaboration (2935 authors)Aguilar-Saavedra, Juan AntonioAmor Dos Santos, Susana PatriciaAnjos, NunoCantrill, RobertCarvalho, JoãoCastro, Nuno FilipeConde Muiño, PatriciaCosta Batalha Pedro, RuteDa 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, Helmut2019-02-032019-02-032014-01-20http://dx.doi.org/10.1016/j.physletb.2013.12.010http://hdl.handle.net/10400.26/26490A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb$^{-1}$ data sample of proton–proton collisions at √s = 7 TeV recorded with the ATLAS detector at the LHC, events consistent with ttbar production and decay into a single charged lepton final state are reconstructed. For each event, the mass difference between the top and anti-top quark candidate is calculated. A two b-tag requirement is used in order to reduce the background contribution. A maximum likelihood fit to these per-event mass differences yields $\Delta m ≣ m_t - m_{\bar{t}}$ = 0.67 ± 0.61(stat) ± 0.41(syst) GeV, consistent with CPT invariance.engjournal article2019-02-03