Colloquia

This presentation is an expanded version of the talk delivered during the award session of the Division of Nuclear Physics (DNP) at the APS Global Summit in Anaheim, CA, on March 19, 2025.

It highlights major 21st-century advancements in hadronic and nuclear physics, through deep exclusive processes, particularly the 3D imaging—or tomography—of the proton’s internal structure. These efforts are shedding light on the gravitational form factors of the proton, offering transformative insights into its mechanical properties, which have never been explored experimentally. This sets the stage for a new era of understanding in nuclear and hadron physics.

To provide context, I will briefly revisit key discoveries in particle physics from the early 20th century through the 1970s, which laid the groundwork for Jefferson Lab’s innovative accelerator design. These breakthroughs enabled unprecedented precision in electron scattering experiments and informed the development of high-performance experimental equipment.

Within one of Jefferson Lab’s experimental halls, Hall B, I will discuss the challenges of building next-generation large acceptance detectors and the resulting scientific breakthroughs. These include insights into the proton’s excitation spectrum as studied in the “missing resonances” program, and the spatial structure of excited states—helping to distinguish between genuine three-quark states and dynamically generated resonances.

Finally, I will follow up on what began as the “proton spin puzzle,” and how recent experimental progress at Jefferson Lab is revealing saturation of the effective strong force at large distances.