  We show that role of nonperturbative input in the $b$-space QCD resummation
formalism for heavy boson transverse momentum ($Q_T$) distribution strongly
depends on collision energy $\sqrt{S}$. At collider energies, the larger
$\sqrt{S}$ is, the weaker role nonperturbative input plays, and better
predictive power the $b$-space resummation formalism has.
