# Axion clockworks from heterotic M-theory: the QCD-axion and its ultra-light companion

## TL;DR

This paper applies a heterotic M-theory clockwork mechanism to identify a QCD-axion candidate within the preferred decay constant range and predicts an accompanying ultra-light axion coupled to hidden sectors.

## Contribution

It introduces a novel application of heterotic M-theory to generate axions with specific properties, including a QCD-axion candidate and ultra-light axions, expanding the axion landscape.

## Key findings

- Identifies a QCD-axion candidate with decay constant around 10^{11} GeV.
- Predicts the existence of at least one ultra-light axion coupled to hidden sectors.
- Provides a framework linking heterotic M-theory to observable axion phenomenology.

## Abstract

A previously discussed clockwork mechanism within heterotic M-theory is applied to its axion landscape. We identify a unique candidate for a QCD-axion with a decay constant in the preferred "axion window" around $10^{11}\,$GeV. It is accompanied by at least one ultra-light axion that couples predominantly to hidden sector gauge groups.