Theoretical Study of Nucleon Structure and Hadronic Interactions

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Neutrons and protons, the constituents of the atomic nucleus, are composed of quarks. We study the quark substructure of nucleons and also particles that contain heavy quarks. We focus on approximate symmetries of quarks such as flavor symmetry and charge symmetry, which would be an exact symmetry if protons and neutrons were identical. We plan to study high-energy nuclear reactions that produce heavy quarks, where we can differentiate between "extrinsic" quarks produced by gluon splitting and "intrinsic" heavy quarks such as appear in meson-cloud models. We will particularly focus on possibilities for observing heavy-quark production at a future electron-ion collider. We will continue our investigations of the effects of Regge exchange on hard exclusive processes. Amplitudes that include Regge exchange violate the factorization theorem for hard exclusive processes and thus acquire a measurable dependence on the four-momentum transfer. We will carry out simulations of electrons or atoms moving in small two-dimensional nanoscale systems, where the wave nature of particles produces large effects. This work involves training of undergraduates and postdocs, who become experts in complex systems with application to technology, defense, communications and finance. Recent postdocs have included several women. The principal investigator gives seminars on advances in physics for non-scientists, increasing scientific literacy in the general population. The PI is recently participating in a "Big History" collaboration involving physicists, astronomers, geologists, biologists and anthropologists. This collaboration has produced two symposia, a museum exhibit and a Web site, with plans to produce DVDs and a book in the future.