Stellar Light Scattering as a Probe for a Braneworld-Induced Baryogenesis Scenario

A recent baryogenesis scenario [Phys. Rev. D 110, 023520 (2024)], rooted in a two-brane Universe model, proposed a solution to the matter-antimatter asymmetry through the dynamics of a new pseudo-scalar field. In the present paper, one investigates the phenomenological consequences of this proposal. One shows that the associated boson could persist as a relic from the early Universe, forming a subdominant component of dark matter. While its overall cosmological density is small ($\approx 0.2\%$), one demonstrates that a one-loop process facilitates an ultra-weak coupling to photons, leading to a distinctive scattering signature. One argues that this effect could produce a faint, glowing halo around massive, hot stars, characterized by a unique spectral decay. Detecting or constraining this elusive light with current and future instruments like the JWST would provide a powerful and direct observational test of the underlying braneworld dynamics and its connection to baryogenesis.