Nonperturbative contributions to a resummed leptonic angular   distribution in inclusive $Z/\gamma^*$ boson production
  We summarize a new analysis of the distribution $\phi_{\eta}^{*}$ of charged leptons produced in decays of $Z$ and $\gamma^{*}$ bosons in the Collins-Soper-Sterman (CSS) formalism for transverse momentum resummation. By comparing the $\phi_{\eta}^{*}$ distribution measured at the Tevatron with the resummed CSS cross section with approximate ${\cal O}(\alpha_{s}^{2})$ Wilson coefficients, we constrain the magnitude of the nonperturbative Gaussian smearing factor and analyze its uncertainty caused by variations in scale parameters. We find excellent agreement between the $\phi_{\eta}^{*}$ data and our theoretical prediction, provided by the \textsc{ResBos} resummation program. The nonperturbative factor that we obtained can be used to update resummed QCD predictions for precision measurements in inclusive $W$ and $Z$ production and for comparisons to various models of nonperturbative dynamics. 
Marco Guzzi and Pavel M. Nadolsky
hep-ph