Related paper J/$ψ$ suppression at forward rapidity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV Invariant mass spectrum of $\mu^{+} \mu^{-}$ pairs (solid black circles)with $p_{\rm{t}} \geq 0$ and $2.5 < y < 4 $ in the 0%-80% most central Pb-Pb collisions.[png] [pdf]