Figure 6

$\bf{Left:}$ $R_{\rm {PbPb}}$ of electrons and muons [31] from heavy-flavour hadron decays in 10% most central Pb-Pb collisions shown together with $R_{\rm {pPb}}$ of electrons from minimum bias proton-lead collisions at $\sqrt{s_{\rm NN}}$ = 5.2 TeV [61]. $\bf{Right:}$ $R_{\rm {PbPb}}$ of electrons in semi-peripheral Pb-Pb collisions (50-80% selection for electrons and 40-80% for muons.