Observational tests of inflation

TL;DR

This paper reviews key observational predictions of inflationary cosmology, emphasizing how upcoming data can test, falsify, or support the model through perturbation behavior, flatness, and tensor modes, including potential model distinctions.

Contribution

It introduces a method for reconstructing the inflaton potential without relying on the slow-roll approximation, enhancing the ability to test inflation models.

Findings

Perturbations crossing inside the Hubble radius in their growing mode can be observationally tested.

Spatial flatness and tensor perturbations support inflation but do not exclude it.

A technique for inflaton potential reconstruction without slow-roll assumptions is proposed.

Abstract

We are on the verge of the first precision testing of the inflationary cosmology as a model for the origin of structure in the Universe. I review the key predictions of inflation which can be used as observational tests, in the sense of allowing inflation to be falsified. The most important prediction of this type is that the perturbations will cross inside the Hubble radius entirely in their growing mode, though nongaussianity can also provide critical tests. Spatial flatness and tensor perturbations may offer strong support to inflation, but cannot be used to exclude it. Finally, I discuss the extent to which observations will distinguish between inflation models, should the paradigm survive these key tests, in particular describing a technique for reconstruction of the inflaton potential which does not require the slow-roll approximation.