Study of Hadronic Structure Using Electromagnetic Probes

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The research being done by Professors Daniel Carman and Kenneth Hicks of the Department of Physics and Astronomy at Ohio University is conducted in the area of intersection between nuclear and particle physics. One goal is to study the production of subatomic particles having at least one "strange" quark in their makeup. The strange quark is heavier than the conventional "up" or "down" quarks that make up common particles found in the nucleus, like the proton and the neutron. Interestingly, studies involving particles with "strangeness" represent a new way to investigate the dynamics and structure of matter composed of non-strange quarks. Thisis accomplished by understanding how particles without strangeness decay intoparticles containing these strange quarks. These experimental studies provide more information and constraints for the underlying theory of the quark structure of particles and their excited states known as quantum chromodynamics (QCD). One possible extension to the known set of subatomic particles would be the discovery of "exotic" particles which are allowed by the rules of QCD, but not yet seen experimentally. In particular, the glue which binds quarks can itself carry a portion of the spin quantum numbers of a particle, and these particles are predicted to exist. Understanding the nature of this glue is one of the mostimportant unanswered question in the field of nuclear physics. Experiments at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in Newport News, VA, where Carman and Hicks do their research, are searching for signs of exotic particles, which (if found) will extend our knowledge of the strong force that binds quarks together into subatomic particles and into the very structure of the matter around us.