u/Ashamed-Travel6673

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https://arxiv.org/abs/2605.13958

Abstract: We propose an explanation for the dark matter-baryon coincidence based on collapsing Z_N domain walls, which form a novel compact baryonic state: the baryoid. A baryoid has an asteroid-scale mass and up-to-nuclear-scale energy density, and can serve as a dark matter candidate. Starting from equal baryon numbers in the domains formed in the early universe, the collapse of the domain walls after the QCD phase transition leads to a baryon-number ratio of (N-1):1 between the false- and true-vacuum domains. Since baryons are slightly lighter in the false-vacuum domains than in the true-vacuum domain, the resulting dark matter-to-baryon energy-density ratio is naturally close to, but slightly smaller than, (N-1):1, or 6:1 for N=7. We calculate the domain-wall dynamics and the efficiency of baryon-number trapping, derive the resulting baryoid properties, and discuss a broad set of phenomenological probes.

https://arxiv.org/abs/2605.13958

Abstract: We propose an explanation for the dark matter-baryon coincidence based on collapsing Z_N domain walls, which form a novel compact baryonic state: the baryoid. A baryoid has an asteroid-scale mass and up-to-nuclear-scale energy density, and can serve as a dark matter candidate. Starting from equal baryon numbers in the domains formed in the early universe, the collapse of the domain walls after the QCD phase transition leads to a baryon-number ratio of (N-1):1 between the false- and true-vacuum domains. Since baryons are slightly lighter in the false-vacuum domains than in the true-vacuum domain, the resulting dark matter-to-baryon energy-density ratio is naturally close to, but slightly smaller than, (N-1):1, or 6:1 for N=7. We calculate the domain-wall dynamics and the efficiency of baryon-number trapping, derive the resulting baryoid properties, and discuss a broad set of phenomenological probes.