Jump Starting the Dark Sector with a Phase Transition

TL;DR

This paper explores how dark sectors can be populated via phase transitions during the early universe, especially when particle production is suppressed during inflation, leading to potential dark matter candidates with specific mass ranges.

Contribution

It demonstrates that large-scale inflation naturally induces phase transitions in dark sectors, affecting dark matter abundance and predicting specific mass ranges depending on the transition timing.

Findings

Dark sectors undergo phase transitions controlled by the Hubble parameter.

Particle production during inflation is suppressed, avoiding isocurvature constraints.

Dark matter mass is predicted to be around 10^8 GeV for transitions during radiation domination.

Abstract

We study the possibility to populate the dark sector through a phase transition. We will consider secluded dark sectors made of gauge theories, Randall-Sundrum scenarios and conformally coupled elementary particles. These sectors have in common the fact that the action is approximately Weyl invariant, implying that particle production due to time dependent background is strongly suppressed. In particular no significant production takes place during inflation allowing to avoid strong isocurvature constraints from CMB. As we will show, if the scale of inflation is large compared to the dynamical mass scale, these sectors automatically undergo a phase transition that in the simplest cases is controlled by the Hubble parameter. If the phase transition takes place during reheating or radiation the abundance obtained can be larger than particle production and production from the SM plasma. For phase transitions completing during radiation domination, the DM mass is predicted in the range $10^8$ GeV while larger values are required for phase transitions occurring during reheating.