Comparison between data (red circles) and Monte Carlo (black open triangles)for several topological variables used to select secondary vertices. Thetop panels correspond tothe $\Kzs$ candidates selected in a $\pm 20 $MeV$/c^2$ invariant mass window around the nominal mass The distribution of the DCA between the positive daughter track and the primary vertex and the DCA distribution between the two daughters tracks are displayed in the left and the right top panels respectively. On the bottom panels, the same distributions are shown for the $\mathrm {\overline{\Lambda}}$ candidates selected in a $\pm 8 $MeV$/c^2$ invariant mass window around the nominal mass.