Measurement of the mass difference between top and anti-top quarks in pp collisions at $\sqrt(s) = 7$ TeV using the ATLAS detector

A 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.