Effective noise in a stochastic description of inflation - art. no. 084008

Stochastic description of inflationary spacetimes emulates the growth of va cuum fluctuations by an effective stochastic ''noise field" which drives th e dynamics of the volume-smoothed inflation. We investigate statistical pro perties of this field and find its correlator to be a function of distance measured in units of the smoothing length. Our results apply for a wide cla ss of smoothing window functions and are different from previous calculatio ns by Starobinsky and others who used a sharp momentum cutoff. We also disc uss the applicability of some approximate noise descriptions to simulations of stochastic inflation.