Braneworld baryogenesis and QCD-era magnetogenesis: a predictive link

We demonstrate that primordial magnetic fields (PMF) play a decisive role in the braneworld baryogenesis scenario of Sarrazin and Stasser [17], where C/CP violation arises from the coupling of visible and hidden matter-antimatter sectors through a pseudo-scalar field. Although this mechanism generates baryon number efficiently only after the quark-hadron transition, by incorporating a realistic stochastic PMF within a semi-analytical framework, we find that matching the observed baryon–antibaryon asymmetry robustly requires PMF strengths of order 10¹⁰ 10 10 T right after the transition, in agreement with causal QCD-era magnetogenesis. We further reveal that magnetic fluctuations drive the baryon-density spectrum to white noise on large scales, yielding an isocurvature component compatible with Cosmic Microwave Background (CMB) bounds. This establishes a predictive link between the braneworld baryogenesis model and realistic early-Universe magnetic fields.