Erratum: Statistical anisotropy in the inflationary universe

Understand

An error was made when calculating the amplitude of the perturbed scalar mode after Hubble-radius crossing.

• When corrected, it eliminates the leading term in the statistical anisotropy of the power spectrum, reducing it from the previously claimed upper estimate of $\lesssim 10^{-2}$ to the level of at most $10^{-6}$, which is beyond the possibility of detection.
• The general conclusion is that a single-field inflationary scenario cannot produce statistical anisotropy of appreciable magnitude.