Electroweak Baryogenesis by Black Holes

The Standard Model extended by a real scalar singlet $S$ with an approximate $\mathbb{Z}_2$ symmetry offers a minimal framework for realizing electroweak baryogenesis (EWBG) during a first-order electroweak phase transition. In this work, we explore a novel mechanism where spontaneous $\mathbb{Z}_2$ breaking enables EWBG via domain walls separating two distinct phases of the $S$ field. These domain walls feature restored (or weakly broken) EW symmetry in their cores and sweep...

We study a scenario in which the baryon asymmetry is created through Hawking radiation from primordial black holes via a dynamically-generated chemical potential. This mechanism can also be used to generate the observed dark matter abundance, regardless of whether or not the black holes fully evaporate. In the case that evaporation ceases, the observed dark matter abundance is generically comprised of both relic black holes and an asymmetric dark matter component. We show tha...

We propose that modifications to the Higgs potential within a narrow atmospheric layer near the event horizon of an astrophysical black hole could significantly enhance the rate of sphaleron transitions, as well as transform the Chern-Simons number into a dynamic variable. As a result, sphaleron transitions in this region occur without suppression, in contrast to low-temperature conditions, and each transition may generate a substantially greater baryon number than would be p...

Domain walls are a type of topological defects that can arise in the early universe after the spontaneous breaking of a discrete symmetry. They can form in several beyond the Standard Model theories with an extended Higgs sector such as the Next to-Two-Higgs-Doublet model (N2HDM). In this work, we discuss the domain wall solution related to the singlet scalar of the N2HDM and demonstrate the possibility of restoring the electroweak symmetry inside and in the vicinity of the d...

We find out that baryon numbers of the matter fallen into black holes are rapidly washed-out by investigating the radiation-ball description of the black holes. The radiation-ball solution, which was derived by analyzing the backreaction of the Hawking radiation into space-time and is identified as a black hole, consists of the radiation gravitationally-trapped into the ball and of a singularity. The baryon number of the black hole is defined as that of the radiation in the b...

Phase transitions are part of everyday life, yet are also believed to be part of the history of our universe, where the nature of particle interactions change as the universe settles into its vacuum state. The discovery of the Higgs, and measurement of its mass suggests that our vacuum may not be entirely stable, and that a further phase transition could take place. This article is based on a talk in the Oldenberg Series, and reviews how we find the probability of these phase...

We propose a novel mechanism of electroweak baryogenesis based on the standard model only and explaining the coincidence between the baryon and dark matter densities in the Universe, as well as the observed value of the baryon-to-photon ratio. In our scenario, large curvature fluctuations slightly below the threshold for Primordial Black Hole (PBH) formation locally reheat the plasma above the sphaleron barrier when they collapse gravitationally but without forming a black ho...

Baryogenesis during the electroweak phase transition is a plausible scenario for for the origin of matter in the Universe. Furthermore, it has the advantage over other scenarios in that one can imagine that much of the physics involved may be experimentally probed before long. In the past year a consensus has developed about major mechanisms involved. In this talk I give an overview of the standard picture, and discuss briefly the advances over the past year that suggest elec...

In this paper, we discuss the Higgs vacuum stability around evaporating black holes. We provide a new approach to investigate the false vacuum decay around the black hole and clearly show how vacuum fluctuations of the Higgs induce a gravitational collapse of the vacuum. Furthermore, we point out that the backreaction of the Hawking radiation can not be ignored and the gravitational vacuum decay is exponentially suppressed. However, a large number of the evaporating (or evapo...

We have refined our previously suggested scenario of generation of the cosmological baryon asymmetry through an asymmetric capture of baryons and antibaryons by primordial block hole arXiv:2009.04361. It is found that in the limit of weak interactions of hypothetical heavy baryons with the primeval plasma the effect can be strongly enhanced and the observed magnitude of the asymmetry can be obtained for a wide range of the model parameters.