GUT Baryogenesis With Primordial Black Holes

TL;DR

This paper explores how primordial black holes could have contributed to GUT baryogenesis by producing GUT bosons via Hawking evaporation, potentially overcoming temperature constraints and sphaleron washout issues.

Contribution

It introduces a novel mechanism where primordial black holes assist GUT baryogenesis, expanding viable scenarios beyond traditional high-temperature models.

Findings

Black hole evaporation can produce GUT bosons regardless of early universe temperature.

Black holes evaporating after electroweak phase transition can avoid sphaleron washout.

A wide parameter space exists where black holes facilitate baryon asymmetry generation.

Abstract

In models of baryogenesis based on Grand Unified Theories (GUTs), the baryon asymmetry of the universe is generated through the CP and baryon number violating, out-of-equilibrium decays of very massive gauge or Higgs bosons in the very early universe. Recent constraints on the scale of inflation and the subsequent temperature of reheating, however, have put pressure on many such models. In this paper, we consider the role that primordial black holes may have played in the process of GUT baryogenesis. Through Hawking evaporation, black holes can efficiently generate GUT Higgs or gauge bosons, regardless of the masses of these particles or the temperature of the early universe. Furthermore, in significant regions of parameter space, the black holes evaporate after the electroweak phase transition, naturally evading the problem of sphaleron washout that is normally encountered in GUT models based on $SU(5)$. We identify a wide range of scenarios in which black holes could facilitate the generation of the baryon asymmetry through the production and decays of GUT bosons.