The proton in 3D

Protons and neutrons constitute the building blocks of normal matter, accounting for almost all the mass of our world. We are still far from understanding the intricacies and mysteries of their inner structure. In the course of several decades of successful studies, we dedicated our efforts to delving deeper and deeper into them. A few years ago, thanks to a fruitful synergy of theoretical and experimental progress, we started to collect unprecedented multi-dimensional images of the distribution of quarks and gluons inside protons and neutrons. These pictures of the universe within the nucleon challenge our comprehension of the underlying theory of quark and gluon dynamics (quantum chromo-dynamics—QCD) and at the same time put us face to face with fundamental questions, such as: What is the shape of the nucleon? What is the spin of the nucleon coming from