  Soft function relevant for transverse-momentum resummation for Drell-Yan or
Higgs production at hadron colliders are computed through to three loops in the
expansion of strong coupling, with the help of bootstrap technique and
supersymmetric decomposition. The corresponding rapidity anomalous dimension is
extracted. An intriguing relation between anomalous dimensions for
transverse-momentum resummation and threshold resummation is found.
