| The energy spectra of the selected (a) single electron, (b) single muon, and (c) single tau candidates. The sum of the different lepton energy spectra is shown in (d). The points are data, the hatched histograms correspond to the background contribution. The open histograms show the expected signal from $\mathrm{e} \nu_\mathrm{e} \ell \nu_\ell$ final states as predicted by the EXCALIBUR Monte Carlo. |