Moduli Entrapment with Primordial Black Holes

TL;DR

This paper proposes that primordial black holes in the early universe can effectively address the moduli overshoot problem in string cosmology by capturing and slowing moduli evolution, facilitating inflation.

Contribution

It introduces a novel mechanism where a gas of black holes in the early universe traps moduli, providing a new solution to the overshoot problem in string cosmology.

Findings

Black hole gas captures moduli near the Planck scale.

Moduli are slowed down and can roll into an inflationary valley.

Black holes redshift away during cosmic expansion.

Abstract

We argue that primordial black holes in the early universe can provide an efficient resolution of the Brustein-Steinhardt moduli overshoot problem in string cosmology. When the universe is created near the Planck scale, all the available states in the theory are excited by strong interactions and cosmological particle production. The heavy states are described in the low energy theory as a gas of electrically and magnetically charged black holes. This gas of black holes quickly captures the moduli which appear in the relation between black hole masses and charges, and slows them down with their vevs typically close to the Planck scale. From there, the modulus may slowly roll into a valley with a positive vacuum energy, where inflation may begin. The black hole gas will redshift away in the course of cosmic expansion, as inflation evicts black holes out of the horizon.