Stellar light scattering as a probe for a braneworld-induced baryogenesis scenario

Abstract A recent baryogenesis scenario (Sarrazin and Stasser in 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 ( $$\approx 0.2\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>0.2</mml:mn> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> ), 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.