Scatter plot of $(m^{2} - m^{2}_{\rm \bar{t}})$ measured with the TOF detector versus $p_{\mathrm{T}}$. Only those tracks are shown which pass the pre-selection done by applying a 3$\sigma$ cut on the TPC d$E$/d$x$. The $p_{\mathrm{T}}$-region in which the candidates are identified on a track-by-track basis is shown as red box.