Bubbletrons: Ultrahigh-Energy Particle Collisions and Heavy Dark Matter at Phase Transitions

TL;DR

This paper introduces 'bubbletrons', ultra-high-energy particle collisions at phase transition bubble walls, linking them to potential dark matter production and gravitational wave signals across a wide frequency spectrum.

Contribution

It proposes the concept of bubbletrons, calculates the maximum dark matter mass they can produce, and explores their connection to gravitational wave signals from cosmological phase transitions.

Findings

Maximum dark matter mass ranges from 10^5 to 10^15 GeV depending on phase transition scale.

Bubbletrons can produce ultra-high-energy particles during cosmological phase transitions.

Gravitational waves from bubbletrons span from nanohertz to megahertz frequencies.

Abstract

We initiate the study of `bubbletrons', by which we mean ultra-high-energy collisions of the particle shells that generically form at the walls of relativistic bubbles in cosmological first-order phase transitions (PT). As an application, we calculate the maximal dark matter mass $M_{DM}$ that bubbletrons can produce in a $U(1)$ gauge PT, finding $M_{DM} \sim 10^5/10^{11}/10^{15}$ GeV for PT scales $v_\phi \sim 10^{-2}/10^3/10^9$ GeV. Bubbletrons realise a novel link between ultra-high-energy phenomena and gravitational waves (GW) sourced at the PT, from nanohertz to megahertz frequencies.