Limits on light primordial black holes from high-scale leptogenesis

TL;DR

This paper explores how the evaporation of light primordial black holes could dilute lepton asymmetry, imposing constraints on their properties and revealing an interplay with neutrino masses in the context of high-scale leptogenesis.

Contribution

It provides the first detailed analysis of the constraints on light primordial black holes from their impact on high-scale leptogenesis and neutrino mass scales.

Findings

Primordial black hole evaporation can dilute lepton asymmetry after sphaleron freeze-out.

Strong constraints are derived on primordial black hole mass and abundance.

An interplay between black hole parameters and active neutrino mass scale is identified.

Abstract

We investigate the role that the evaporation of light primordial black holes may have played in the production of the baryon asymmetry of the Universe through the high-scale leptogenesis. In particular, for mass of primordial black hole in the range [$10^6$-$10^9$] g, we find a dilution of thermally generated lepton asymmetry via entropy injection in the primordial plasma after the sphaleron freeze-out. As a consequence, we can put strong constraints on the primordial black hole parameters, showing the mutual exclusion limits between primordial black holes and high-scale leptogenesis. Remarkably, we point out an interplay between the upper bound on the initial abundance of primordial black holes and the active neutrino mass scale.