New spin on Einstein's non-symmetric metric tensor
  A solution to the gravitational field equations based on a non-symmetric metric tensor is examined. Unlike Einstein's interpretation of electromagnetism, or Moffat's generalized gravity, it is shown that the non-symmetric part of the metric tensor is the potential of the spin field. This is in agreement with string theory and provides a natural coupling between gravitation and strings. 
Richard T. Hammond
gr-qc