Equations of Motion and Energy-Momentum 1-Forms for the Coupled   Gravitational, Maxwell and Dirac Fields
  A theory where the gravitational, Maxwell and Dirac fields (mathematically represented as particular sections of a convenient Clifford bundle) are supposed fields in Faraday's sense living in Minkowski spacetime is presented. In our theory there exist a genuine energy-momentum tensor for the gravitational field and a genuine energy-momentum conservation law for the system of the interacting gravitational, Maxwell and Dirac fields. Moreover, the energy-mometum tensors of the Maxwell and Dirac fields are symmetric, and it is shown that the equations of motion for the gravitational potentials is equivalent to Einstein equation of General Relativity (where the second member is the sum of the energy-momentum tensors of the Maxwell, Dirac and interaction Maxwell-Dirac fields) defined in an effective Lorentzian spacetime, whose use is eventually no more than a question of mathematical convenience. 
Waldyr A. Rodrigues Jr. and Samuel Augusto Wainer
math-ph math.MP