Sean Fleming, Professor of Physics, University of Arizona
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Abstract: Nucleons are the fundamental building blocks of all atomic nuclei and make up essentially all the visible matter in the universe. The nucleon is not static but has complex internal structure, the dynamics of which are only beginning to be revealed in modern experiments. Understanding this structure in terms of the constituents of the nucleon is a great intellectual challenge and a major theme of the DOE Nuclear Theory program. In Quantum Chromodynamics (QCD), the theory of the strong interactions, the nucleon emerges as a strongly interacting, relativistic bound state of quarks and gluons (collectively called partons). Owing to the color confinement, a defining property of QCD, even the most advanced detector cannot see partons as they are forever bound inside hadrons. Several decades of experiments have taught us about how partons share the momentum of a fast-moving nucleon. They have not, however, resolved the question of how partons share the nucleon’s spin and build up other nucleon intrinsic properties, such as its mass and magnetic moment. A new accelerator, the electron ion collider (EIC) is scheduled for construction beginning in 2024. This machine is designed to yield much greater insight into nucleon structure by facilitating multi-dimensional maps of the distributions of partons in space, momentum, spin, and flavor. In this talk I will give an overview of our current understanding of the internal structure of nucleons. I will also cover recent theoretical advances that, in conjunction with data from the EIC and large hadron collider make it possible to significantly extend our understanding of the nucleon. ** Refreshments served from 2:45pm – 3:00pm in PAS 218. Thank you. **