# The Marshland Conjecture

## TL;DR

The paper introduces the concept of the Marshland as a boundary region in string theory separating consistent theories from the swampland, highlighting its fractal nature and implications for light axions and symmetries.

## Contribution

It proposes the existence of the Marshland as a fractal boundary within string theory, providing new insights into the landscape, swampland, and associated symmetries.

## Key findings

- The Marshland likely has a fractal structure.
- It contains theories with many light axions.
- The Marshland constitutes most of the landscape volume.

## Abstract

We posit the existence of the Marshland within string theory. This region is the boundary between the landscape of consistent low-energy limits of quantum gravity, and the swampland of theories that cannot be embedded within string theory because they violate certain trendy and obviously uncontroversial conjectures. The Marshland is probably fractal, and we show some pretty pictures of fractals that will be useful in talks. We further show that the Marshland contains theories with a large number of light axions, allowing us to cite lots of our own papers. We show that the Marshland makes up most of the volume of the landscape, and admits a novel, weakly broken $\mathbb{Z}_2$ Marshymmetry that we find strong evidence for by considering a carefully crafted example.