Graviton propagator in de Sitter space

We consider the graviton propagator in a de Sitter background. The propagator depends upon the choice of a gauge-fixing term L_gauge=1/2F², and we consider the ``{ε} gauges'' with Fᵛ=∇ᵤ(hᵘᵛ-{ε}gᵘᵛ{h}^{{σ}}_σ). We show that the propagator is completely finite and has no infrared divergences provided that {ε} is not given certain ``exceptional'' values. It is only for these ``exceptional'' values of {ε} that the propagator has an infrared divergence. We then show that in these exceptional cases the divergences are gauge artifacts and are not physical: they make no contribution to any physical tree-level scattering amplitudes. Furthermore, we show that at one-loop order the zero modes which arise (only) if {ε} is given one of the exceptional values are canceled by the Faddeev-Popov ghosts. There is thus no evidence that the de Sitter background is inconsistent when gravitational fluctuations are considered.