Constraints imposed byCPconservation in the presence of pseudoparticles

Abstract

We elaborate on an earlier discussion of $\mathrm{CP}$ conservation of strong interactions which includes the effect of pseudoparticles. We discuss what happens in theories of the quantum-chromodynamics type when we include weak and electromagnetic interactions. We find that strong $\mathrm{CP}$ conservation remains a natural symmetry if the full Lagrangian possesses a chiral U(1) invariance. We illustrate our results by considering in detail a recent model of (weak) $\mathrm{CP}$ nonconservation.