Gluon PDF constraints from the ratio of forward heavy-quark production at the LHC at $$\sqrt{S}=7$$ and 13 TeV

We discuss production of charm and bottom quarks at forward rapidity in pp collisions at the LHC, updating the QCD predictions for the run at \(\sqrt{S}=13\) TeV. We show that, while the absolute rates suffer from large theoretical systematics, dominated by scale uncertainties, the increase relative to the rates precisely measured at 7 TeV can be predicted with an accuracy of a few percent, sufficient to highlight the sensitivity to the gluon distribution function.