A Theoretical Study of Hadronic Interactions and the Structure of the Nucleon

Indiana University, Bloomington IN

Investigators

Abstract

This renewal proposal requests continued NSF funding of a research program currently sup- ported by the grant NSF-PHY-0070368. The major proposed topics lie in the area of \quark{ nuclear physics," to study the quark sub{structure of strongly interacting particles. Particular attention is on approximate symmetries of QCD, particularly favor and charge symmetry. Symmetry violation provides a \mirror" to identify and quantify non-perturbative physics. This research should shed light on the detailed properties of the fundamental constituents of matter, with emphasis on the validity of favor and charge symmetry, the spin dependence of parton distributions, and nuclear modification of parton properties. One product of this grant would be a comprehensive review of charge symmetry at both low and high energies, emphasizing our current understanding of the role of the up-down quark mass difference in generating charge symmetry violation over a wide variety of energies and physical processes. Models developed by the PI will be employed to investigate recent neutrino results, which are suggested to show physics beyond the Standard Model. The structure of baryon resonances will be investigated through a relativistic code developed explicitly to study these systems. New features of these calculations should allow a more realistic description of the structure of resonances in the .25N system. It is also proposed to study binding and scattering of particles in constrained 2-D systems, relevant to quantum wires and photonic crystals. Prior research in this area culminated in a monograph published by Springer-Verlag. Continuing studies involve collaboration with an experimental colleague combining theoretical studies of novel geometries with experiments on these systems. In all proposed areas, there is close linkage between theory and experiment. Some recent predictions by the PI are being studied at facilities such as LEP, HERA and the Tevatron. The baryon resonance work proposed here is relevant to data taken at the CLAS detector at Jefferson Lab. The PI is involved in studies for a possible new facility, an Electron-Ion Collider (EIC), which was favorably assessed in the recent NSAC Long-Range Plan for nuclear physics. The PI is a co-author on recent EIC planning efforts that include a Web site and CD- ROM containing a Whitepaper on EIC physics. The PI is Director of the Indiana University Nuclear Theory Center (NTC). Currently the NTC has four postdocs and visitors, three of whom are women. In several instances, women working at NTC have received joint support from two or more sources, combining federal, university or foreign contributions. The PI has set up international collaborations between the NTC and physics institutes in Australia, Japan and Germany. The PI has mentored 9 undergraduate researchers in summer REU programs during the past 8 years. They have given talks on their research at subsequent workshops and professional meetings, and have collaborated on publications with the PI. The research proposed here will provide training and mentoring for both postdoctoral research associates, and undergraduate physics majors.