Eliminating infrared divergences in an inflationary cosmology
  We study the infrared divergences arising from gravitational loops in the
standard cosmological perturbation theory. We provide a simple solution to the
problem at all orders of cosmological perturbation theory by redefining the
perturbation theory in terms of a local observer. We propose to reformulate the
standard perturbations in the in-in formalism, and obtain an infrared safe
perturbation theory. Our results do not depend on any infrared cutoffs or
similar parameters. We then present an explicit example of graviton one-loop
corrections, and briefly discuss non-gaussianities.
