Primordial Black Holes from First-Order Phase Transition in the xSM

TL;DR

This paper explores how a supercooled first-order phase transition in the singlet extended Standard Model could produce primordial black holes with Earth-like masses, which might be detectable through gravitational waves and microlensing.

Contribution

It demonstrates that the xSM can produce Earth-mass primordial black holes during a supercooled phase transition at the electroweak scale, linking particle physics with cosmological observations.

Findings

Primordial black holes formed have a narrow Earth-mass distribution.

Future LISA observations could confirm or exclude this PBH formation scenario.

PBHs may explain some ultrashort microlensing events observed by OGLE.

Abstract

Supercooled first-order phase transition (FOPT) can lead to the formation of primordial black holes (PBHs). This scenario imposes stringent requirements on the profile of the effective potential. In this work, we use the singlet extended Standard Model (xSM) as a benchmark model to investigate this possibility at the electroweak scale. The PBHs formed during a supercooled FOPT have a narrow mass distribution around the mass of Earth. This distribution is closely tied to the temperature at which the PBHs form, corresponding to the FOPT at the electroweak scale. This scenario can be probed with microlensing experiments, space-based gravitational wave detectors, and collider experiments. Remarkably, the future space-based gravitational wave detector LISA will hold the potential to either confirm this PBH scenario in the xSM or completely rule it out for extremely small total dark matter fraction made of PBHs, down to $f_{\rm PBH}> 10^{-300}$. Interestingly, our findings suggest that PBHs within the xSM framework may align with observations of the six ultrashort timescale events reported by the OGLE microlensing experiment.