Theoretical Nuclear Physics

Progress toward understanding the structure and behavior of strongly interacting many-body systems requires detailed theoretical study. The theoretical physics program concentrates on the development of fundamental and phenomenological models of nuclear behavior. In some systems, the nucleons move quite freely and independently, while in others they behave in a very cooperative and coherent manner. Understanding this dichotomy and searching for new modes of collective motion is a central problem of contemporary many-body theory. Many of the theoretical techniques developed for such strongly interacting systems have proven to be very useful in other fields of physics; particularly condensed matter physics.

Although nuclei behave very often as collections of nucleons, other degrees of freedom are also present. The basic particles of the strong interaction are not mesons and nucleons, but their constituent particles, quarks. Probing the quark content of nuclei (e.g., developing an understanding of how and when the basic degrees of freedom embodied in quarks can or cannot be subsumed in hadron degrees of freedom) is one of the most challenging unanswered problems of nuclear science and is under active investigation at the Institute.

Characterizing the properties of nuclear matter under extreme conditions of density is a new frontier activity in nuclear science. The study of the very dense states of matter, which are expected to be created in the initial stages of heavy-ion collisions, is a tremendous theoretical and experimental challenge. The theoretical aspects of this problem are being examined with the objectives of developing a comprehensive theory for heavy-ion collisions and proposing various signatures for hot dense nuclear matter and the quark-gluon plasma.