Electroweak Gauge-Boson and Higgs Production at Small $q_T$: Infrared Safety from the Collinear Anomaly.

Thomas Becher, Matthias Neubert & Daniel Wilhelm
We study the differential cross sections for electroweak gauge-boson and Higgs production at small and very small transverse-momentum $q_T$. Large logarithms are resummed using soft-collinear effective theory. The collinear anomaly generates a non-perturbative scale $q_*$, which protects the processes from receiving large long-distance hadronic contributions. A numerical comparison of our predictions with data on the transverse-momentum distribution in Z-boson production at the Tevatron and LHC is given.