Note about the spin connection in general relativity

In general relativity the fermions are treated from the perspective of the gauged Lorentz group and by introducing the corresponding gauge fields the spin connection. This procedure is intimately related to the so-called "vielbein" formalism and stems from the general structure that can be associated to a manifold, the affine connection. In this work we derive the correct spin connection based only on the general covariance of the theory, on the gauged Lorentz symmetry and on the known space-time properties of fermion bilinears generalized to the curved space. Our result coincides exactly with the spin connection obtain through the tetrad formalism.