  Following an earlier derivation by Catani-de Florian-Grazzini (2000) on the
scheme dependence in the Collins-Soper-Sterman (CSS) resummation formalism in
hard scattering processes, we investigate the scheme dependence of the
Transverse Momentum Distributions (TMDs) and their applications. By adopting a
universal $C$-coefficient function associated with the integrated parton
distributions, the difference between various TMD schemes can be attributed to
a perturbative calculable function depending on the hard momentum scale. We
further apply several TMD schemes to the Drell-Yan process of lepton pair
production in hadronic collisions, and find that the constrained
non-perturbative form factors in different schemes are remarkably consistent
with each other and with that of the standard CSS formalism.
