Baryogenesis via Asymmetric Evaporation of Primordial Black Holes

Abstract

We revisit baryogenesis from the asymmetric evaporation of light primordial black holes, focusing on scenarios where gravitational effects induce a matter antimatter asymmetry. In particular, we consider a higher-dimension operator coupling the Kretschmann scalar to a baryon-number-violating current which generates an effective chemical potential at the black hole horizon and leads to asymmetric Hawking radiation. Relative to earlier studies, we account for entropy dilution from evaporation, incorporate chemical potential dependent greybody factors and numerically track the fully coupled evolution of a PBH population in an expanding universe. We show that the observed baryon asymmetry can be reproduced within a viable region of parameter space for several PBH mass spectra including log-normal, critical-collapse, and power-law distributions.