Equivalence of the Duffin-Kemmer-Petiau and Klein-Gordon-Fock equations

A strict proof of the equivalence of the Duffin Kemmer Petiau and Klein-Gor don-Fock theories is presented for physical S-matrix elements in the case o f charged scalar particles minimally interacting with an external or quanti zed electromagnetic field. The hamiltonian canonical approach to the Duffin -Kemmer Petian theory is first developed in both the component and the matr ix form. The theory is then quantized through the construction of the gener ating functional for the Green's functions, and the physical matrix element s of the S-matrix are proved to be relativistic invariants. The equivalence of the two theories is then proved for the matrix elements of the scattere d scalar particles using the reduction formulas of Lehmann, Symanzik, and Z immermann and for the many-photon Green's functions.