Characterize the proton’s three-dimensional structure and parton correlations

Characterize the full three-dimensional structure of the proton and the correlations among its constituent partons, including their transverse spatial distributions and interparton dependencies.

Background

The paper identifies the longitudinal momentum structure of the proton through parton distribution functions as increasingly well studied, while emphasizing that the proton’s complete spatial structure and correlations among different partons remain poorly constrained. These properties are central to understanding multiparton interactions, double parton scattering, and the impact-parameter dependence of hadron collisions.

The proposed measurements of proton overlap and its dependence on partonic momentum fraction are motivated in part by the need to obtain information about this unresolved three-dimensional structure and the associated parton correlations.