Speaker
Description
Extracting information on the three-dimensional structure of hadrons from transverse-momentum data is a challenging task, as it requires disentangling well-controlled perturbative contributions from genuinely non-perturbative effects, which are unavoidably influenced by phenomenological assumptions. This subtle interplay often obscures the interpretation of phenomenological analyses, even when they provide an accurate description of experimental data. In this talk, I present a systematic procedure to analytically continue perturbative calculations into the deep infrared region, below the 1–2 GeV scale. I identify two primary sources of non-perturbative effects: the low-energy behavior of the strong coupling and that of the parton distribution functions. This framework turns transverse-momentum-dependent observables into a privileged probe of strong interactions in a poorly understood regime, offering novel insights into the strong coupling and PDFs where they are least constrained.