# Axions of Evil

## TL;DR

This paper develops a systematic framework for multiple axion theories, revealing a novel alignment mechanism that simplifies complex models, and demonstrates their potential to explain dark matter, inflation, and the cosmological constant without fine-tuning.

## Contribution

It introduces a new alignment concept in multi-axion theories, enabling analytical tractability and exploring their implications for cosmology and dark matter.

## Key findings

- Exponential number of meta-stable vacua in multi-axion models.
- Light axions can account for dark matter with correct abundance.
- Tunneling and inflation scenarios compatible with observed universe features.

## Abstract

We provide a systematic framework for theories of multiple axions. We discover a novel type of "alignment" that renders even very complex theories analytically tractable. Theories with about 100 axions and random parameters have an exponential number of meta-stable vacua and accommodate a diverse range of inflationary observables. Very light fields can serve as dark matter with the correct abundance. Tunneling from a minimum with large vacuum energy can occur via a thin-wall instanton and be followed by a sufficient period of slow-roll inflation that ends in a vacuum containing axion dark matter and a cosmological constant with a value consistent with observation. Hence, this model can reproduce many macroscopic features of our universe without tuned parameters.