  In flat space, gamma5 and the epsilon tensor break the dimensionally
continued Lorentz symmetry, but propagators have fully Lorentz invariant
denominators. When the Standard Model is coupled with quantum gravity gamma5
breaks the continued local Lorentz symmetry. I show how to deform the Einstein
lagrangian and gauge-fix the residual local Lorentz symmetry so that the
propagators of the graviton, the ghosts and the BRST auxiliary fields have
fully Lorentz invariant denominators. This makes the calculation of Feynman
diagrams more efficient.

High Energy Physics - Theory