The invariant mass (upper panel) and pseudo-proper decay length (lowerpanel) distributions for $\textrm{e}^{+} \textrm{e}^{-}$ pairs with $p_{T} > 1.5$ GeV$/c$ in Pb-Pb collisions in the centrality interval $10$-$50$% at $\sqrt{s_{NN}}$ =2.76 TeV. The projections of the maximum likelihood fit used toextract $f_{B}$ are superimposed to the data.