Primordial Black Hole Hot Spots and Out-of-Equilibrium Dynamics

TL;DR

This paper develops a framework to analyze how evaporating primordial black holes create hot spots that affect baryogenesis and dark matter production in the early Universe, revealing new effects on these processes.

Contribution

It introduces a general method to calculate particle escape probabilities from PBH-induced hot spots and explores their impact on leptogenesis and dark matter relics.

Findings

PBH hot spots can enable right-handed neutrinos to generate BAU below electroweak scale

Particles thermalized in hot spots may not contribute to dark matter relic abundance

Hot spots significantly influence early Universe baryogenesis and dark matter scenarios

Abstract

When light primordial black holes (PBHs) evaporate in the early Universe, they locally reheat the surrounding plasma, creating hot spots with temperatures that can be significantly higher than the average plasma temperature. In this work, we provide a general framework for calculating the probability that a particle interacting with the Standard Model can escape the hot spot. More specifically, we consider how these hot spots influence the generation of the baryon asymmetry of the Universe (BAU) in leptogenesis scenarios, as well as the production of dark matter (DM). For leptogenesis, we find that PBH-produced right-handed neutrinos can contribute to the BAU even if the temperature of the Universe is below the electroweak phase transition temperature, since sphaleron processes may still be active within the hot spot. For DM, particles emitted by PBHs may thermalise with the heated plasma within the hot spot, effectively preventing them from contributing to the observed relic abundance. Our work highlights the importance of including hot spots in the interplay of PBHs and early Universe observables