Ghost properties of generalized theories of gravitation

We investigate theories of gravitation, in which spacetime is non-Riemannian and the metric $g_{\mu \nu }$ is nonsymmetric, for ghosts and tachyons, using a spin-projection operator formalism. Ghosts are removed not by gauge invariance but by a Lagrange multiplier $W_{\mu }$, which occurs due to the breaking of projective invariance in the theory. Unified theories based on a Lagrangian containing a term $\lambda g^{\mu \nu }{g}_{\left[\mu \nu \right]}$ are proved to contain ghosts or tachyons.