Elementary and Composite Particles
Abstract
It is shown for two simple fixedsource theories with one stable excited state of the source that (1) a knowledge of the physical Smatrix elements of the theory is sufficient to decide if the state is associated with an elementary particle or a composite particle, and (2) the theory in which the particle is composite corresponds to the elementaryparticle theory in the limit of vanishing wave function renormalization constant of the elementary particle. The distinction between elementary and composite particle is related to a generalization of Levinson's theorem, and it is made plausible that this generalization is valid in local field theory. In an Appendix, the result (2) is generalized, and an application to the dispersiontheoretic treatment of rearrangement collisions is suggested.
 Publication:

Physical Review
 Pub Date:
 November 1961
 DOI:
 10.1103/PhysRev.124.1258
 Bibcode:
 1961PhRv..124.1258V