Efficient electroweak baryogenesis by black holes

Abstract

A novel cosmological scenario, capable of generating the observed baryon number at the electroweak scale for very small charge parity violating angles, is presented. The proposed mechanism can be applied in conventional Friedmann-Robertson-Walker cosmology, but becomes extremely efficient due to accretion in the context of early cosmic expansion with high-energy modifications. Assuming that our Universe is a Randall-Sundrum brane, baryon asymmetry can easily be produced by Hawking radiation of very small primordial black holes. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. The black hole's lifetime is prolonged due to accretion, resulting in strong efficiency of the baryon producing mechanism. The black hole mass range allowed by the mechanism includes masses that are energetically favored to be produced from interactions around the higher dimensional Planck scale.