Holographic Limitations of the Effective Field Theory of Inflation

Holographic considerations may provide a glimpse of quantum gravity beyond what is currently accessible by other means. Here we apply holography to inflationary cosmology. We argue that the appropriate holographic bound on the total entropy in the inflationary perturbations is given by the {\it difference} of the area of the apparent horizon in the slow-roll approximation and its exact value near the end of inflation. This implies that the effective field theory of the inflaton weakly coupled to gravity requires modifications below the Planck scale. For a conventional model of inflation this scale is of order of the GUT scale, $\Lambda_{UV} \la 10^{16} GeV$, but could be considerably lower. Signatures of such new physics could show up in the CMB.