# Crystalline droplets with emergent topological color-charge in many-body systems with sign-changing interactions

## TL;DR

This paper introduces a new type of self-bound droplet with an emergent topological color charge in many-body systems, formed via sign-changing interactions, with potential realization in cold atom experiments.

## Contribution

It presents a novel self-bound droplet model with topological color charge arising from sign-changing interactions, and proposes an experimental realization with cold atoms in optical cavities.

## Key findings

- Droplets form through spontaneous crystallization into topologically distinct domains.
- Each droplet's color charge influences mutual interactions, being attractive or repulsive.
- The model predicts nontrivial viscous dynamics in droplet plasmas.

## Abstract

We introduce a novel type of self-bound droplet which carries an emergent color charge. We consider a system of particles hopping on a lattice and interacting via a commensurately sign-changing potential which is attractive at a short range. The droplet formation is heralded by spontaneous crystallization into topologically distinct domains. This endows each droplet with an emergent color charge governing their mutual interactions: attractive for equal colors and repulsive otherwise. The number of allowed colors is fixed only by the discrete spatial symmetries of the sign-changing part of the interaction potential. With increasing interaction range, the droplets become progressively more mobile, with their color charge still being energetically protected, allowing for nontrivial viscous dynamics of the interacting droplet plasmas formed during cooling. Sign-changing potentials with a short-range attraction appear quite naturally for light-mediated interactions and we concretely propose a realization in state-of-the-art experiments with cold atoms in a multimode optical cavity.