Revisiting the Affleck-Dine mechanism for primordial black hole formation

TL;DR

This paper examines primordial black hole formation via the Affleck-Dine mechanism, highlighting constraints from baryon asymmetry and proposing an alternative leptogenesis-based scenario that aligns with observational data.

Contribution

It identifies limitations of previous AD baryogenesis models and introduces a novel AD leptogenesis approach involving Q-balls for PBH formation.

Findings

Previous inhomogeneous AD baryogenesis scenarios are constrained by baryon asymmetry outside PBHs.

The proposed AD leptogenesis scenario with Q-balls can produce PBH abundances consistent with observations.

The model explains PBH formation in both stellar-mass and supermassive black hole regimes.

Abstract

We study a primordial black hole (PBH) formation scenario based on the Affleck-Dine (AD) mechanism and investigate two PBH mass regions: $M \sim 30 M_\odot$ motivated by the LIGO-Virgo observations of the binary black hole mergers and $M \gtrsim 10^4 M_\odot$ motivated by the observations of supermassive black holes at the center of galaxies. In the previous studies, it has been considered that the inhomogeneous AD baryogenesis generates regions with a large baryon asymmetry, some of which collapse into PBHs. In this paper, we show that this scenario is severely constrained due to the baryon asymmetry remaining outside PBHs, which would spoil the success of the big bang nucleosynthesis. Then, we propose an alternative scenario where the AD leptogenesis results in the inhomogeneous formation of Q-balls with lepton charges, which collapse into PBHs. As a result, we find that our scenario can explain the favorable PBH abundance without conflicting with the observational constraints.