Cosmological UV/IR Divergences and de-Sitter Spacetime
  We consider one loop graviton corrections to scalar field Green's functions
in the de Sitter phase of an inflationary space-time, a topic relevant to the
computation of cosmological observables beyond linear order. By embedding
de-Sitter space into an ultraviolet complete theory such as M-theory we argue
that the ultraviolet (UV) cutoff of the effective field theory should be taken
to be fixed in physical coordinates, whereas the infrared (IR) cutoff is
expanding as space expands. In this context, we demonstrate how to implement
three different regularization schemes -- the brute force cutoff
regularization, dimensional regularization and Pauli-Villars regularization --
obtaining the same result for the scalar propagator if we use any of the three
regularization schemes.
