The particle aspect of meson theory

Abstract

1. Introduction For many years a central problem of theoretical physics has been to set up a satisfactory relativistic theory of elementary particles. This problem is yet far from solution, the notorious occurrence of infinite self-energies and similar divergencies having hitherto frustrated all attempts at complete formulation. Nevertheless, definite advances towards the understanding of the general problem have recently been made, not so much by improvement of the theory as by a more detailed study of all its possible types and variants and the resulting clarification of the essential underlying principles. The picture of an elementary relativistic quantum-mechanical “particle ” can now be roughly outlined as follows: The “exact theory” is one of quantized waves, the particle characteristics appearing as consequences of the non-commutation of the wave amplitudes. There exist possible theories with any given integral or half-integral value s of the “ spin” of the particle, the number of independent states of polarization of the corresponding waves then being 2 s + 1 = N (Fierz 1939; Fierz and Pauli 1939).