Protons and neutrons(nucleons) are the basic constituents of matter. However, t has become clear that these particles are composed of even more fundamental particles called quarks. The description of the properties of protons and neutrons, and their interactions, using quarks as fundamental degrees of freedom, represents a significant part of our research. In addition, we can also study the properties of mesons. The exchange of mesons between nucleons gives rise to their interaction at relatively low energies. If we work at low energy, we can use effective theories that are meant to describe only the low-energy properties of the systems considered (The theory of strong interactions, quantum chromodynamics, is very hard to treat in the low-energy domain and effective theories have found extensive application.) The fact that free quarks are not seen in nature leads one to say that quarks are `confined`. Introduction of a model of confinement in the effective theories we study is an important part of our program. In addition, we study the nature of the potentials found in nuclei. These potentials have been found to have an interesting relativistic structure. (They contain parts which transform differently when one describes the system with alternate coordinate frames, making use of Lorentz transformations. Our detailed analysis of the force between nucleons allows us to understand the properties of the potentials found in nuclei from a fundamental point of view. The success of the entire project will yield a good understanding of mesons, nucleons, and nuclei that has its basis in quantum chromodynamics, the modern theory of strong interactions.
