boson production with the Hadron Structure Oriented approach

We present a first practical implementation of a recently proposed hadron structure oriented (HSO) approach to TMD phenomenology applied to Drell-Yan like processes, including lepton pair production at moderate Q² and Z₀ boson production. We compare and contrast general features of our methodology with other common practices and emphasize the improvements from our approach that we view as essential for applications where extracting details of nonperturbative transverse hadron structure is a major goal. These include the HSO’s preservation of a basic TMD parton-model-like framework even while accounting for full TMD factorization and evolution, explicit preservation of the integral relationship between TMD and collinear pdfs, and the ability to meaningfully compare different theoretical models of nonperturbative transverse momentum dependence. In our examples, we show that there is significant sensitivity at moderate Q² to both the form of the nonperturbative transverse momentum dependence and the parametrization of collinear

parton densities. However, we also find that evolving to Q² = M_Z² without fitting results in a satisfactory postdiction of existing data for Z₀ production, nearly independently of the modeling of nonperturbative transverse momentum dependence. We argue that this demonstrates that moderate Q measurements should be given greater weight than high Q measurements in extractions of nonperturbative transverse momentum dependence. We also obtain new extractions of the nonper-

turbative Collins-Soper kernel within the HSO approach. We discuss its features and compare with some earlier extractions.