An important quest in modern nuclear physics concerns the theoretical understanding of the structure of nucleons (protons and neutrons) in terms of quarks, antiquarks and gluons, the degrees of freedom of quantum chromodynamics (QCD), the fundamental theory of strong interactions. In this project, the investigator and his students will advance the development of theory necessary to understand experiments at the Thomas Jefferson National Laboratory, Brookhaven National Laboratory, and other facilities world-wide. In addition to providing theoretical support for existing and future experimental programs, the benefits of this project include training for graduate students. The project will also offer research opportunities for undergraduate students at the frontiers of theoretical nucleon structure research.
This project will explore nucleon structure in terms of transverse momentum dependent parton distribution functions (TMDs). Based on a QCD factorization formalism, TMDs are a useful tool in the study of high-energy reactions. As compared to the familiar and better known collinear parton distribution functions which describe processes when no final-state transverse momenta are resolved, TMDs offer detailed information about dynamics. They provide access to parton orbital motion and aspects of spin-orbit correlations when polarized beams and targets are explored. The goal of this project is to advance the current understanding of the properties of TMDs in a non-perturbative framework. The specific objectives of the project are: (1) determine the non-perturbative properties of TMDs at a low initial scale, (2)identify model-independent signatures of chiral symmetry breaking with focus on sea quark effects, (3) explore phenomenological applications and present predictions for experiments. The tools employed in this project include the use of perturbative evolution equations, dynamical models, and effective chiral theories.
