Non-Singular Magnetic Monopole
  Magnetic Monopole is a cosequence of the existence of the duality symmetry in electromagnetics. Although, no conclusive experimental evidence have so far been found but the subject is still of much interest to physicist. The theory of magnetic monopoles was first proposed by Dirac in 1931 and soon after it was studied by physicist of many deciplines specially particle physics, quantum field theory and non-linear Soliton equations. One important consequence of the magnetic monopole theory is the quantization of the electric charge which was first derived by Dirac. In the definition of the classicaql magnetic monopole, the concept of Dirac string is used. dirac string is the locus of the points where the vector potential is nopt well-behave. On the other hand by introducing the idea of magnetic monopoles, Maxwell's equations became symmetrical with respect to the magnetic and electric fields, but they still remain unsymmetrical as far as the scalar and the vector potentials are concerned. In this work the electric and magnetic fields are redifined in termes of some new scalar and vector potentials, respectively, as a result of which the Maxwell's equations become symmetrical with respect to the potentials, too. One advantage of using this formulation is that one can discard the Dirac string all together. Finally, definition of the new potentials guarantees the lorentz invariance of equations. 
Siamak Khademi, Masoumeh Shahsavari, Amir Hosein Saeid