Duffin-Kemmer-Petiau and Klein-Cordon-Fock equations for electromagnetic, Yang-Mills and external gravitational field interactions: proof of equivalence

Starting from the Generating functional for the Green Function (GF), constr ucted from the Lagrangian action in the Duffin-Kemmer-Petiau (DKP) theory ( L-approach) we strictly prove that the physical matrix elements of the S-ma trix in DKP and Klein-Gordon-Fock (KGF) theories coincide in cases of inter acting spin O particles with external and quantized Maxwell and Yang-Mills fields and in case of external gravitational field (without or with torsion ), For the proof we use the reduction formulas of Lehmann, Symanzik and Zim mermann (LSZ). We prove that many photons and Yang-Mills particles GF coinc ide in both theories too. (C) 2000 Elsevier Science B.V. All rights reserve d.