Hadron Physics and Non-Perturbative QCD Modeling

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This research project addresses mechanisms underlying the strong interaction of subatomic physics in terms of the confined quarks and gluons described by that part of the Standard Model known as Quantum Chromodynamics (QCD). We implement a continuum nonperturbative approach based on the Dyson-Schwinger equations of QCD which preserves the short distance renormalization group behavior of perturbative QCD while the infrared domain is described by one parameter to generate the empirical amount of dynamical chiral symmetry breaking. The latter phenomenon is the source for the generation of at least 98% of the mass of known stable matter in the universe, and it guides the development of our theoretical methods.This work will analyze and interpret information about the quark and gluon structure of sub-atomic particles produced by the Jefferson Laboratory at Newport News Virginia (JLab), and provide predictions for the experiments anticipated from the upgrade currently being undertaken. Theoretical work of this type informs and motivates a portfolio of fundamental physics programs at sub-atomic physics laboratories across the world. Specific physics issues addressed include parton distributions of the pion and kaon mesons, the transition or generalized parton distributions of the pion and kaon mesons, the elastic and transition form factors of pions for a complete range of momentum transfer, and an extension to nucleon parton distributions, and their ratios. We anticipate a by-product will be a new understanding of the mass scale for transition from non-perturbative to perturbative dynamics in the pion charge form factor. Broader impacts of the program include the cross-fertilization of nuclear and particle physics, a return on the investment in the experimental facilities at JLab and RHIC, and integration of research and education through the research training of graduate students in connection with undergraduate teaching. The interactions of graduate students with scientists who are prominent nationally and internationally is a contribution to the nation's infrastructure for research and education. The PI uses examples from this research program to illustrate key elements of core graduate classes in Quantum Mechanics and Nuclear and Particle Physics. The PI supervises an informal seminar course for graduate students and postdoctoral associates to discuss and present aspects of QCD and field theory that underly this research program. The collaboration with overseas colleagues will enhance international cooperation in science research and education.