TMD Evolution: Matching SIDIS to Drell-Yan and W/Z Boson Production

TL;DR

This paper investigates the QCD evolution of transverse momentum dependent observables in semi-inclusive deep inelastic scattering and Drell-Yan processes, establishing a matching framework with existing resummation methods and predicting spin asymmetries for future experiments.

Contribution

It introduces a unified evolution approach for TMD observables that matches existing resummation techniques and applies it to predict spin asymmetries in various hadronic collision processes.

Findings

The evolution equations accurately describe unpolarized cross sections from 2 to 100 GeV^2.

Successful matching between direct evolution and Collins-Soper-Sterman resummation with non-perturbative form factors.

Predictions for Sivers asymmetries in Drell-Yan and W/Z production for upcoming experiments.

Abstract

We examine the QCD evolution for the transverse momentum dependent observables in hard processes of semi-inclusive hadron production in deep inelastic scattering and Drell-Yan lepton pair production in $pp$ collisions, including the spin-average cross sections and Sivers single transverse spin asymmetries. We show that the evolution equations derived by a direct integral of the Collins-Soper-Sterman evolution kernel from low to high Q can describe well the transverse momentum distribution of the unpolarized cross sections in the Q^2 range from 2 to 100 GeV^2. In addition, the matching is established between our evolution and the Collins-Soper-Sterman resummation with b*-prescription and Konychev-Nodalsky parameterization of the non-perturbative form factors, which are formulated to describe the Drell-Yan lepton pair and W/Z boson production in hadronic collisions. With these results, we present the predictions for the Sivers single transverse spin asymmetries in Drell-Yan lepton pair production and $W^\pm$ boson production in polarized pp and $\pi^- p$ collisions for several proposed experiments. We emphasize that these experiments will not only provide crucial test of the sign change of the Sivers asymmetry, but also provide important opportunities to study the QCD evolution effects.