Simple exercises to flatten your potential

TL;DR

This paper discusses how the backreaction of heavy scalar fields can naturally flatten the inflationary potential, making certain inflation models more viable in UV-complete theories like axion monodromy.

Contribution

It demonstrates that backreaction effects are a general mechanism for flattening inflationary potentials in UV-complete models, extending previous specific examples.

Findings

Backreaction can flatten quadratic potentials to linear or power-law forms.

Flattened potentials are more generic at large field values.

Special compactifications can preserve quadratic potentials, but are less common.

Abstract

We show how backreaction of the inflaton potential energy on heavy scalar fields can flatten the inflationary potential, as the heavy fields adjust to their most energetically favorable configuration. This mechanism operates in previous UV-complete examples of axion monodromy inflation - flattening a would-be quadratic potential to one linear in the inflaton field - but occurs more generally, and we illustrate the effect with several examples. Special choices of compactification minimizing backreaction may realize chaotic inflation with a quadratic potential, but we argue that a flatter potential such as power-law inflation $V(\phi) \propto \phi^p$ with $p<2$ is a more generic option at sufficiently large values of $\phi$.