QCD predictions for new variables to study dilepton transverse momenta at hadron colliders

The D0 Collaboration has recently introduced new variables, aT and ϕ⁎ to more accurately probe the low QT domain of Z boson production at hadron colliders than had been previously possible through a direct study of the QT distribution. The comparison of such accurate data to precise theoretical predictions from QCD perturbation theory will yield important information on the ability of resummed QCD predictions as well as parton shower models to describe the low QT domain and should enable more stringent constraints on non-perturbative effects. In the present Letter we provide analytical predictions for the above mentioned variables, that contain resummation of large logarithms, including next-to-next-to-leading logarithmic (NNLL) terms, supplemented by exact O(αs2) next-to-leading order calculations from MCFM.