Generating the dark matter mass from the QCD vacuum: a new approach to the mass aspect of the dark matter–baryon coincidence problem

The comparable abundances of dark matter and baryons imply a deep connection between the dark sector and the QCD sector. In asymmetric dark matter models, the number densities of both sectors are ensured to be similar. However, a complete solution should also include a mechanism relating their masses. In this study, we explore a new mechanism where an O(Λ QCD) O ( Λ QCD ) dark matter mass arises from the QCD vacuum. The idea is realized by a strongly coupled chiral dark sector, featuring a light composite fermion as the dark matter. Its mass is generated through the vacuum misalignment induced by QCD, ensuring the mass to be comparable with baryons. The model also features additional light bosons, including GeV-scale dark pions and a composite QCD axion.