A unification scheme for the Einstein and Maxwell theories

A unification scheme for the Einstein and Maxwell theories is developed within a Riemann-Cartan geometry. The electromagnetic field is introduced at the level of the connection and it is, in fact, coded in the torsion. Within our framework, the unification of the massless spin-one and spin-two fields requires the inclusion of a massless spin-zero field, whose introduction may give rise to a non-constant gravitational coupling. However, for the case of dust-filled homogeneous and isotropic universe the result is essentially the same as the one supplied by general relativity.