A Quantum field theory of dyons
  We construct a classical field theory action which upon quantization via the functional integral approach, gives rise to a consistent Dirac-string independent quantum field theory. The approach entails a systematic derivation of the correlators of all gauge invariant observables, and also of charged dyonic fields. Manifest SO(2)-duality invariance and Lorentz invariance are ensured by the PST-approach. 
Kurt Lechner