Efficiency of $\phi$ (stars) and $\mathrm {\Xi^{-}+\overline{\Xi}^{+}}$ (diamonds)as a function of $\pT$. The uncertainties correspond to the statistics in the Monte Carlo sample used to compute the corrections The efficiency is limited by the branching ratio represented by a solid arrow for $\mathrm {\Xi^{-}+\overline{\Xi}^{+}}$ (0.636)and by a dashed arrow for $\phi$ (0.492)