The theory of scattering is developed from first principles with strict attention to the question of the preparation of the state vector of the system appropriate to a description of scattering. The connection between the present formulation and the more conventional interaction representation and $S$ matrix presentations is traced. The wave matrix of Møller is introduced and the existence of bound states is discussed in connection with it. A number of applications to rather involved processes are discussed. Finally, the problem of self-energies in field-theoretic scattering calculations is treated.

• Received 23 January 1953

DOI:https://doi.org/10.1103/PhysRev.91.398