Darkogenesis

TL;DR

This work explores models in which the dark sector itself generates the observed matter-antimatter asymmetry through a first-order phase transition, thereby connecting the baryon density to the dark matter density. The authors implement a minimal hidden sector with a non-Abelian gauge group and a global $U(1)_D$ that is anomalous, enabling dark-number violation via dark sphalerons, and they study two concrete transfer mechanisms to the SM: higher-dimension operators and electroweak sphalerons mediated by messenger fields. They present a low-scale model with perturbative transfer yielding $m_X \approx 5$ GeV and a high-scale model with messenger leptodarks producing $m_{DM} \approx 1$ GeV, analyzing the necessary annihilation of the symmetric DM component and the associated cosmological and collider constraints. The paper highlights phenomenological predictions, including direct-detection prospects and potential gravitational-wave signals from the dark-phase transition, and outlines future avenues for constructing diverse darkogenesis scenarios.

Abstract

In standard models of baryogenesis and of dark matter, the mechanisms which generate the densities in both sectors are unrelated to each other. In this paper we explore models which generate the baryon asymmetry through the dark matter sector, simultaneously relating the baryon asymmetry to the dark matter density. In the class of models we explore, a dark matter asymmetry is generated in the hidden sector through a first order phase transition. Within the hidden sector, it is easy to achieve a sufficiently strong first order phase transition and large enough $CP $ violation to generate the observed asymmetry. This can happen above or below the electroweak phase transition, but in both cases significantly before the dark matter becomes non-relativistic. We study examples where the Asymmetric Dark Matter density is then transferred to the baryons both through perturbative and non-perturbative communication mechanisms, and show that in both cases cosmological constraints are satisfied while a sufficient baryon asymmetry can be generated.

Figures (2)

• Figure 1: A schematic of the classes of models we consider. The asymmetry is generated in the hidden sector via a first order phase transition and then transferred to the visible sector either via a higher dimension operator or electroweak sphalerons.
• Figure 2: The spectrum of the minimal dark sector. Among the states carrying $U(1)_D$, only the lightest, $X$ (the DM particle), is shown.