Electromagnetic Duality, Quaternion and Supersymmetric Gauge Theories of   Dyons
  Starting with the generalized potentials, currents, field tensors and electromagnetic vector fields of dyons as the complex complex quantities with real and imaginary counter parts as electric and magnetic constituents, we have established the electromagnetic duality for various fields and equations of motion associated with dyons in consistent way. It has been shown that the manifestly covariant forms of generalized field equations and equation of motion of dyons are invariant under duality transformations. Quaternionic formulation for generalized fields of dyons are developed and corresponding field equations are derived in compact and simpler manner. Supersymmetric gauge theories are accordingly reviewed to discuss the behaviour of dualities associated with BPS mass formula of dyons in terms of supersymmetric charges. Consequently, the higher dimensional supersymmetric gauge theories for N=2 and N=4 supersymmetries are analysed over the fields of complex and quaternions respectively. 
H. Dehnen and O. P. S. Negi