Ratio of the $\pT$-differential production cross section of muons from heavy-flavour hadron decays at forward rapidity in pp collisions at $\sqrt s$ = 7 TeV to that at $\sqrt s$ = 5.02 TeV. Statistical uncertainties (bars) and systematic uncertainties (boxes) are shown. The normalisation uncertainty contains the uncertainties on the luminosity at the two centre-of mass energies. The ratio is compared with FONLL predictions . See the text for details.