The core principle established is that electromagnetic interaction for a charged relativistic scalar particle is derived by applying minimal coupling substitution to the Klein-Gordon equation, replacing canonical momentum with kinetic momentum coupled to four-potentials ($p^\mu \to p^\mu - eA^\mu$). This theoretical framework reinterprets negative probability density solutions arising in free-field equations as physically meaningful charge densities within a conserved current four-vector $j^\mu$. Consequently, the transition amplitude is rigorously defined as an interaction integral between this quantum mechanical source current and the classical electromagnetic potential field.
The core principle established is that electromagnetic interaction for a charged relativistic scalar particle is derived by applying minimal coupling substitution to the Klein-Gordon equation, replac…