Non-thermal Dark Matter Production from the Electroweak Phase Transition: Multi-TeV WIMPs and "Baby-Zillas"

TL;DR

This paper explores how non-thermal production during a first-order electroweak phase transition can generate super-TeV dark matter particles, including WIMPs and ultra-massive 'Baby-Zillas', potentially explaining the observed relic density.

Contribution

It introduces a mechanism for non-thermal dark matter production at the electroweak transition, applicable to multi-TeV WIMPs and ultra-massive 'Baby-Zillas', expanding dark matter origin scenarios beyond thermal models.

Findings

Dark matter can be produced non-thermally at the electroweak transition.

Super-TeV WIMPs can survive thermalization and account for relic density.

Ultra-massive 'Baby-Zillas' never reach thermal equilibrium, providing alternative dark matter candidates.

Abstract

Particle production at the end of a first-order electroweak phase transition may be rather generic in theories beyond the standard model. Dark matter may then be abundantly produced by this mechanism if it has a sizable coupling to the Higgs field. For an electroweak phase transition occuring at a temperature T_EW ~ 50-100 GeV, non-thermally generated dark matter with mass M_X > TeV will survive thermalization after the phase transition, and could then potentially account for the observed dark matter relic density in scenarios where a thermal dark matter component is either too small or absent. Dark matter in these scenarios could then either be multi-TeV WIMPs whose relic abundace is mostly generated at the electroweak phase transition, or "Baby-Zillas" with mass M_GUT >> M_X >> v_EW that never reach thermal equilibrium in the early universe.