  We study the production of a Standard Model Higgs boson in the gluon-fusion
channel at the 13 TeV LHC. Our results are accurate to the next-to-leading
order in QCD, bar for the lack of some two-loop amplitudes, for up to two extra
jets and are matched to the PYTHIA8 Monte Carlo. We address the impact, at the
level of inclusive rates and of differential distributions, of the merging of
samples characterised by different final-state multiplicities, and of the
effects induced by top and bottom masses through heavy-quark loop diagrams. We
find that both the merging and the heavy-quark masses must be included in the
calculation in order to realistically predict observables of experimental
interest.
