  We present all-order expressions for the leading double-logarithmic threshold
contributions to the quark-gluon coefficient functions for inclusive
Higgs-boson production in the heavy top-quark limit and for Drell-Yan
lepton-pair production. These results have been derived using the structure of
the unfactorized cross sections in dimensional regularization and the large-x
resummation of the gluon-quark and quark-gluon splitting functions. The
resummed coefficient functions, which are identical up to colour factor
replacements, are similar to their counterparts in deep-inelastic scattering
but slightly more complicated.
