Role of nonperturbative input in QCD resummed heavy boson Q_T distribution

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.