  Partonic cross sections for the production of massive objects in hadronic
collisions receive large corrections when the invariant mass of the
initial-state partons is just above the production threshold. Since typically
the center-of-mass energy of the hadronic collision is much higher than the
mass of the heavy objects, it is not obvious that these contributions translate
into large corrections to the hadronic cross section. Using a recent approach
to threshold resummation based on effective field theory, we quantify to which
extent the fall-off of the parton densities at high x leads to a dynamical
enhancement of the partonic threshold region. With the example of Drell-Yan
production, we study the emergence of an effective physical scale
characterizing the soft emissions in the process. We derive compact analytical
expressions for the resummed Drell-Yan cross section and rapidity distribution
directly in momentum space. They are free of Landau-pole singularities and are
trivially matched onto fixed-order perturbative calculations. Evaluating the
resummed cross sections at NNNLL order and matching onto NNLO fixed-order
calculations, we perform a detailed numerical analysis of the cross section and
rapidity distribution in proton-proton collisions.
