Gravitation, torsion, and string theory

The low energy effective Lagrangian of string theory presents us with not only gravity, but the dilaton and the antisymmetric field as well. It is shown that a Brans-Dicke generalization of a metric theory of gravity with torsion that is derived as the exterior derivative of a potential is equivalent to the low energy string theory Lagrangian. This gives all of the fields a physical interpretation in four dimensions and provides an indication that the dilaton represents small corrections to general relativity at large distances.