Filtered Dark Matter at a First Order Phase Transition

TL;DR

This paper introduces a novel dark matter production mechanism during a first order phase transition, where particles are reflected by bubble walls and survive only if they enter the bubbles, allowing for a wide mass range including super-PeV scales.

Contribution

It proposes a new dark matter generation process linked to phase transition bubble dynamics, expanding the viable mass range beyond traditional bounds.

Findings

Dark matter can be produced with masses from GeV to above PeV.

The mechanism allows for parameter space beyond the Griest--Kamionkowski bound.

Current experiments can probe much of the viable parameter space.

Abstract

We describe a new mechanism of dark matter production in the early Universe, based on the dynamics of a first order phase transition. We assume that dark matter particles acquire mass during the phase transition, making it energetically unfavourable for them to enter the expanding bubbles of the massive phase. Instead, most of them are reflected off the advancing bubble walls and quickly annihilate away in the massless phase. The bubbles eventually merge as the phase transition is completed, and only the dark matter particles which have entered the bubbles survive to constitute the observed dark matter today. This mechanism can produce dark matter with masses from the GeV scale to above the PeV scale, including a large region of viable parameter space beyond the Griest--Kamionkowski bound. Current and future direct detection and collider experiments can probe much of the viable parameter space.