On a new unified geometric description of gravity and electromagnetism
  In a previous paper, we have introduced a new unified description of the main equations of the gravitational and of the electromagnetic field, in terms of tidal tensors and connections on the tangent bundle TM of the space-time manifold. In the present work, we relate these equations to variational procedures on the tangent bundle. The Ricci scalar of the proposed connection is dynamically equivalent to the usual Einstein-Maxwell Lagrangian. Also, in order to be able to perform these variational procedures, we find an appropriate completion of the metric tensor (from the base manifold) up to a metric structure on TM. 
Nicoleta Voicu
math-ph gr-qc math.DG math.MP