We present a measurement of the mass difference between top ($t$) and antitop ($\overline{t}$) quarks using $t\overline{t}$ candidate events reconstructed in the final state with one lepton and multiple jets. We use the full data set of Tevatron $\sqrt{s}=1.96\mathrm{TeV}$ proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of $8.7{\mathrm{fb}}^{-1}$. We estimate event by event the mass difference to construct templates for top pair signal events and background events. The resulting mass difference distribution in data compared to signal and background templates using a likelihood fit yields $\Delta M_{\mathrm{top}}=M_t-M_{\overline{t}}=-1.95\pm 1.11(\mathrm{stat})\pm 0.59(\mathrm{syst})\mathrm{GeV}/c^2$ and is in agreement with the standard model prediction of no mass difference.

• Received 23 October 2012

DOI:https://doi.org/10.1103/PhysRevD.87.052013