This paper proposes that dark matter could be made of macroscopic clumps of ordinary quarks and antiquarks. The authors introduce what they call the QCD‑AQN framework. In this picture, these dense aggregates form in the early Universe and are held together by axion domain walls. Axions are hypothetical light particles, and a domain wall is a sheet‑like structure that can form in a field as the Universe cools.

At a high level, the idea uses physics of Quantum Chromodynamics (QCD), the theory of quarks and the strong force, together with axion physics. The dense objects are composite, meaning they are made of many quarks or antiquarks rather than single particles. The axion domain walls provide a stabilising force that can keep these aggregates intact over cosmic time. The authors present this as a single framework that could produce dark matter made of macroscopic nuggets rather than of weakly interacting elementary particles.

A notable claim of the framework is that it can also address the matter–antimatter asymmetry. In other words, the same early‑universe processes that make these quark aggregates could help explain why ordinary matter now outnumbers antimatter. That makes the proposal interesting because it aims to link two major puzzles in cosmology with one mechanism.

The paper pays particular attention to what observations already limit this idea and to how the model could be tested. The authors discuss existing observational constraints and outline observational tests that could support or rule out the scenario. This emphasis on empirical constraints is important because the objects in this model would be macroscopic and could leave different signals than particle dark matter.