Measurement of the mass difference between top and anti-top quarks in pp collisions at √s=7TeV using the ATLAS detector

A measurement of the mass difference between top and anti-top quarks is presented.In a 4.7fb−1 data sample of proton–proton collisions at √s=7TeV recorded with the ATLAS detector at the LHC, events consistent with t¯t 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 yieldsm≡mt−m¯t=0.67±0.61(stat)±0.41(syst)GeV,consistent with CPT invariance.