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The focus of Argonne’s hadron physics to understand how the strong force gives rise to the mass, spin and dynamic structure of protons and neutrons, which make up almost all visible matter in our universe.

The vast majority of the visible mass in the universe is a manifestation of the strong force. This strong force binds quarks and gluons together into protons, neutrons, and nuclei, forming the visible matter surrounding us. We understand the strong force through the theoretical framework of Quantum Chromodynamics (QCD). The strong force is unlike the other interactions, both due to its strength and because gluons, which carry the strong force, couple directly to other gluons. These features make direct calculations in QCD extremely difficult. Even today, scientists using the most powerful computers struggle to compute basic properties.

To study the strong force and QCD, our Medium Energy Physics group conducts state-of-the-art experiments at national laboratories, primarily the Jefferson Lab and Fermilab. Additionally, we leverage investments made by other countries in their facilities to further our research goals. Furthermore, we play a leadership role in the science and design of the next generation of experiments, through strategic investments in the Solenoidal Large Intensity Device (SoLID) program at Jefferson Lab and the future polarized high-luminosity EIC facility.

Furthermore, our Theory group engages in a major theory effort to understand how hadrons emerge from QCD. This allows for critical predictions of hadronic properties that can be tested experimentally and provides tools necessary to interpret experimental data and direct connections to the underlying structure of matter.