Invariant mass distribution for ultra-peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}} } = 2.76$ TeV at $-0.9< y< 0.9$ for events satisfying the event selection in Table 1, in the invariant mass interval $2.2< M_{\rm ll}< 6$ GeV/$c^{2}$. Coherent di-electron and di-muon candidates are summed together. For like-sign pair the penultimate cut in Table 1 is replaced by the request of a same-sign pair.