CHARGE SYMMETRY PROPERTIES AND REPRESENTATIONS OF THE EXTENDED LORENTZ GROUP IN THE THEORY OF ELEMENTARY PARTICLES

The extended Lorentz group, including the complete Lorentz group and charge conjugation, is considered. It is shown that the use of irreducible projective representations of this extended group requires the existence of charge multiplets. Charge symmetry and associated production of strange particles follow from the invariance under reflections and charge conjugation and from the conservation laws for the electric and baryonic charges. The Pauli-Gürsey transformation holds for free nucleons. The extension of the condition of invariance under this transformation to the case of interactions leads to isobaric invariance for strong interactions of all particles.