On the many-body theory for systems consisting of composite particles

Wesley E. Brittin, A.Y. Sakakura

Wesley E. Brittin

Harry L. Sahlin, Judah L. Schwartz

A formalism for treating the many-body problem of composite particles is presented for the case of composite particles consisting of two fermions. Commutation relations for composite-particle operators are derived, as well as a sum rule satisfied by the composite-particle Green's function. In an approximation that shuts off the interactions between composite particles in a consistent manner, the dynamical equation for the one-composite-particle Green's function is solved and the distribution function for the composite particles obtained. Possible applications to real systems are discussed.

Cheng-Li Wu, D.H. Feng

Based on the composite particle representation presented in the last paper (I), a method of solving the many-body problem known as the composite particle approximation is proposed. It is shown that a many-body system can be simplified to a composite particle system (plus one or more uncorrelated basic particles if any existed) if the following conditions are satisfied: 1) the binding energies of the composite particles are much larger than the excitation energies of the system; 2) there is domination of the collective mode for the composite particles. The interactions between the composite particles, as well as the interactions between composite particles and the basic particles can be evaluated from the original particle-particle interactions. Applications of this theory are indicated.

M. Popović‐Božić

Stephen J. Gustafson, Israel Michael Sigal