Probing the Weak and Strong Nature of the Nucleon

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The Idaho State University (ISU) medium-energy nuclear-energy group (PI: Philip Cole and CoPIs: Tony Forest, Mahbub Khandaker, and Dustin McNulty) will perform measurements using electromagnetic and electroweak probes at Jefferson Lab that will enhance our understanding of the fundamental properties and symmetries in nucleons and nuclei. Through their several approved and conditionally-approved experiments, they propose to study the quark/gluon constituents of nucleons at various distance scales, measure the size of the proton, and ascertain the structure of neutron-rich nuclei. This award is a continuation of their work on using both electromagnetic and electroweak probes for exploring the nature of the strong force and the weak force expressed in nucleons and nuclei. The strong force, for example, is responsible for how quarks and gluons arrange themselves into nucleons and how these protons or neutrons subsequently bind into nuclei. This research program broadly addresses the many facets of both the strong and the weak force, namely: how valence quarks self assemble when sea quark and gluon contributions are minimal, the nature of how gluons attach to quarks serving to increase the mass of current quarks to that of constituent quarks, how quarks resonate inside the nucleon to form excited assemblies of quarks, how the weak force is coupled in electron scattering from quarks as well as garnering precise data on the neutron radius as evidenced through parity violation. All these dedicated efforts require a group, who overlap in their work, coordinate local resources and skills, and maintain a solid sense of teamwork. Further, the ISU group is providing a great service to the JLab research community in building, stringing, and instrumenting the CLAS12 Region 1 drift chambers for the 12 GeV upgrade to Jefferson Lab. We are the largest JLab group west of the Mississippi.