Gauging gravity with SO(1,3) for spin-1/2 particles
  We demonstrate, by analogy with electromagnetism, that the geometric content in the theory of gravity is an indirect consequence of the fact that the gauge group in question is the Lorentz group SO(1,3). We hence construct field equations for gravity and a spin-1/2 particle in a gravitational field based on gauge considerations. Furthermore, we derive the weak field and Schroedinger limits of the Dirac equation of the particle in the gravitational field, especially in Fermi normal coordinates and on the equatorial plane of the Kerr geometry, following which we identify the terms to which the electromagnetic potentials A and Phi are analogous. 
Arpan Saha, Banibrata Mukhopadhyay
gr-qc hep-th math-ph math.MP