Large-Scale Suppression from Stochastic Inflation
  We show non-perturbatively that the power spectrum of a self-interacting
scalar field in de Sitter space-time is strongly suppressed on large scales.
The cut-off scale depends on the strength of the self-coupling, the number of
e-folds of quasi-de Sitter evolution, and its expansion rate. As a consequence,
the two-point correlation function of field fluctuations is free from infra-red
divergencies.
