Primordial Black Holes Are True Vacuum Nurseries

TL;DR

This paper proposes a novel method using primordial black hole hot spots to evaluate metastable vacuum decay rates, providing new constraints on electroweak vacuum stability based on black hole mass and energy fraction.

Contribution

It introduces a new approach to calculate vacuum decay rates via black hole hot spots, improving upon previous models and applying it to electroweak vacuum stability constraints.

Findings

Constraints on black hole energy fraction for vacuum stability

New formalism for decay rate calculation avoiding previous inconsistencies

Limits on primordial black hole parameters based on vacuum metastability

Abstract

The Hawking evaporation of primordial black holes (PBH) reheats the Universe locally, forming hot spots that survive throughout their lifetime. We propose to use the temperature profile of such hot spots to calculate the decay rate of metastable vacua in cosmology, avoiding inconsistencies inherent to the Hartle-Hawking or Unruh vacuum. We apply our formalism to the case of the electroweak vacuum stability and find that a PBH energy fraction $\beta > 7\times 10^{-80} (M/g)^{3/2}$ is ruled out for black holes with masses $0.8 g < M < 10^{15} g$.