Infrared logarithms in minisuperspace inflation

We examine the emergence of the infrared logarithms in the cosmological perturbation theory applied to the minisuperspace scalar slow-roll inflation. Not surprisingly, in the single scalar field model the curvature perturbation ζ is conserved and no ln⁡aB behavior appears, where aB(t) is the background scale factor of the universe. On the other hand, in the presence of a spectator scalar the n'th order perturbation theory gives an (ln⁡aB)n correction to ζ. However, a nonperturbative estimate shows that ζ actually becomes the sum of a constant and a mildly evolving ln⁡aB pieces.