Feynman rules for magnetised spin-0 bosons

Solutions of the Klein-Gordon equation are given in the Landau and cylindrical gauges and these are used to calculate explicit forms of the vertex function. From an S-matrix expansion analogous to the spin-1/2 case we obtain the Feynmann rules for magnetised spin-0 particles : the major differences between the spin-1/2 and spin-0 cases are the explicit forms of the respective vertex functions and the addition of a two-photon vertex in the spin-0 case. This additional vertex makes possible a whole new class of Feynman diagrams