Are Inflationary Predictions Sensitive to Very High Energy Physics?

TL;DR

This paper investigates whether inflationary predictions of the early universe are affected by physics at extremely high energies, finding they are generally robust but can be sensitive under specific conditions, allowing potential insights into high-energy physics.

Contribution

The study demonstrates that inflationary predictions are mostly insensitive to high-energy physics, but can be affected in certain scenarios, supporting the reliability of cosmological data analysis.

Findings

Inflationary predictions are robust against most high-energy effects.

Some high-energy effects can influence predictions without violating decoupling.

Searching for small deviations can provide insights into very high energies.

Abstract

It has been proposed that the successful inflationary description of density perturbations on cosmological scales is sensitive to the details of physics at extremely high (trans-Planckian) energies. We test this proposal by examining how inflationary predictions depend on higher-energy scales within a simple model where the higher-energy physics is well understood. We find the best of all possible worlds: inflationary predictions are robust against the vast majority of high-energy effects, but can be sensitive to some effects in certain circumstances, in a way which does not violate ordinary notions of decoupling. This implies both that the comparison of inflationary predictions with CMB data is meaningful, and that it is also worth searching for small deviations from the standard results in the hopes of learning about very high energies.