Darkogenesis (1008.1997v1)

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.

Overview of "Darkogenesis"

In the paper "Darkogenesis," the authors explore novel cosmological models that establish interconnections between baryogenesis and the dark matter (DM) sector, postulating a synchronized genesis of matter-antimatter asymmetry and DM density through a common mechanism in a hidden sector. This investigation presents an intriguing alternative to traditional models where baryogenesis and dark matter production are considered separate phenomena.

The core proposition of this paper is the generation of a dark matter asymmetry through a first-order phase transition in a hidden sector. The pivotal feature of this hidden sector is its capacity to facilitate strong enough first-order phase transitions accompanied by sufficient $CP$ violation to produce the observed baryon asymmetry. This mechanism not only generates the DM abundance but also affects the baryonic content of the universe, offering a unified framework addressing the near equivalence in the densities of baryonic matter and dark matter, which standard models do not inherently predict.

Detailed Mechanism and Model

The model proposed by the authors is robust, involving an initial dark matter asymmetry within the hidden sector catalyzed by a strong first-order phase transition. In this framework, $U(1)_D$, a global symmetry in the dark sector analogous to baryon or lepton number, is anomalous under the non-Abelian gauge interactions of the hidden sector. Sphaleron processes within this hidden sector violate dark number, providing a source of $C$ and $CP$ violation, essential for matter-antimatter asymmetry generation as per the Sakharov conditions.

The subsequent transfer of this asymmetry to the standard model (SM) baryons is explored through both perturbative and non-perturbative mechanisms. The perturbative approach involves higher-dimension operators allowing the dark sector asymmetry to influence the SM baryons directly. Alternatively, non-perturbative processes leverage electroweak sphalerons to catalytically transpose the asymmetry across sectors, furnishing a baryon asymmetry from a pre-existing dark asymmetry.

Implications and Future Directions

The integration of darkogenesis with existing cosmological paradigms offers compelling theoretical implications. By aligning the DM relic density and baryon asymmetry through the same underlying process, the models challenge current understandings and point towards potentially observable consequences, such as new direct detection signals or gravitational wave signatures from the hidden sector phase transition. Moreover, these models could pave the way for refinements in our cosmic evolution simulations and understanding of phase transitions in the early universe.

Future theoretical and experimental investigations might focus on precise tests of these interconnected models. Developing an enriched phenomenological model and conducting laboratory searches for predicted relics or phase transition remnants could provide a powerful cross-verification of the hypothesized synchronization of baryon and dark matter genesis.

In conclusion, "Darkogenesis" presents a comprehensive and theoretically sound framework, revitalizing discussions about the mutual origins of baryons and DM. It showcases an innovative approach within the context of particle cosmology, offering exciting opportunities for further interrogation in both theoretical research and experimental probing of the cosmos.