Baryogenesis and Gravitational Waves from Runaway Bubble Collisions

TL;DR

This paper introduces a new mechanism for baryogenesis involving runaway bubble collisions during a first order phase transition, which can produce gravitational waves detectable by future observatories.

Contribution

It presents a fully calculable model demonstrating how runaway bubble collisions can generate baryonic asymmetry and produce observable gravitational wave signals.

Findings

Baryon asymmetry can be generated at low temperatures.

Gravitational wave signals are potentially detectable by eLISA.

The model evades existing cosmological constraints.

Abstract

We propose a novel mechanism for production of baryonic asymmetry in the early Universe. The mechanism takes advantage of the strong first order phase transition that produces runaway bubbles in the hidden sector that propagate almost without friction with ultra-relativistic velocities. Collisions of such bubbles can non-thermally produce heavy particles that further decay out-of-equilibrium into the SM and produce the observed baryonic asymmetry. This process can proceed at the very low temperatures, providing a new mechanism of post-sphaleron baryogenesis. In this paper we present a fully calculable model which produces the baryonic asymmetry along these lines as well as evades all the existing cosmological constraints. We emphasize that the Gravitational Waves signal from the first order phase transition is completely generic and can potentially be detected by the future eLISA interferometer. We also discuss other potential signals, which are more model dependent, and point out the unresolved theoretical questions related to our proposal.