Backreaction and Stochastic Effects in Single Field Inflation

Understand

The formalism of stochastic inflation is a powerful tool for analyzing the backreaction of cosmological perturbations, and making precise predictions for inflationary observables.

• We demonstrate this with the simple $m^2\phi^2$ model of inflation, wherein we obtain an effective field theory for IR modes of the inflaton, which remains coupled to UV modes through a classical noise.
• We compute slow-roll corrections to the evolution of UV modes (i.e.
• quantum fluctuations), and track this effect from the UV theory to the IR theory, where it manifests as a correction to the classical noise.