Antimatter Domains: What a Homogeneous Bounce Must Avoid
Year: 2026
Type: article
Abstract: Some baryogenesis mechanisms produce the right average asymmetry with the wrong sign in places, leaving antimatter domains. This paper computes two of the constraints such domains face in a bounce cosmology. Diffusion around recombination erases domains smaller than about 6.14e-02 Mpc, with the diffusion length estimated at 1.90e+21 metres from a decoupling time of 1.20e+13 seconds; larger domains survive diffusion but meet the gamma-ray bound, which requires the present domain scale to exceed roughly 20 Mpc if domains exist at all. A bounce that homogenises the sign of the asymmetry avoids the entire problem, and this paper argues that is the only comfortable option: domain-forming mechanisms must either be excluded or pushed to scales so large that the observable universe is effectively single-sign, which is observationally indistinguishable from a homogeneous mechanism. Computed from stated assumptions, not measured.
Author: Aldred, William Alexander
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225828262
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