Theoretical investigations and calculations of low- energy hadron properties and interactions are being conducted in terms of quark and gluon constituents by modeling the large distance behavior of the relativistic field theory known as Quantum Chromodynamics. Two complementary lines of investigation are being followed. The first involves truncation of the Dyson-Schwinger equations of motion, and the second involves use of a model quark field theory to produce an effective field theory of mesons. Specific topics being addressed include meson masses and decays, meson-meson and meson-nucleon interaction coupling constants and form factors, and electromagnetic form factors. The experimental issues being confronted now in experiments at the Jefferson Laboratory are of primary concern within this research program. An extension is being made to address these matters at finite temperature and matter density for application to the experimental program at the Relativistic Heavy Ion Collider facility under construction. The investigations are designed to put onto a theoretical basis those aspects of meson interactions and electromagnetic couplings that have in the past been mainly phenomenological.
