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 root s = 7 TeV recorded with the ATLAS detector at the LHC, events consistent with t (t) over bar 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((t) over bar) = 0.67 +/- 0.61 (stat) +/- 0.41 (syst) GeV, consistent with CPT invariance. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.
Aad, G., Abajyan, T., Abbott, B., Abdallah, J., Abdel Khalek, S., Abdinov, O., et al. (2014). Measurement of the mass difference between top and anti-top quarks in pp collisions at root s=7 TeV using the ATLAS detector. PHYSICS LETTERS. SECTION B, 728, 363-379 [10.1016/j.physletb.2013.12.010].