- The paper presents a comprehensive review of ADM models, linking baryon asymmetry with dark matter density through diverse asymmetry generation mechanisms.
- It examines both minimal and complex hidden sector scenarios, detailing how dark matter may interact with standard model particles and additional dark forces.
- Experimental strategies including direct detection, collider searches, and astrophysical observations are analyzed to constrain the ADM framework.
Insights and Implications of Asymmetric Dark Matter Models
The reviewed paper addresses the asymmetric dark matter (ADM) hypothesis, presenting both the theoretical foundation and phenomenological implications. ADM hypothesizes that the dark matter (DM) density in the universe has a particle-antiparticle asymmetry similar to that which accounts for visible matter (VM) abundance. This hypothesis is driven by the observed proximity between the mass densities of DM and VM, which conventional weakly-interacting massive particle (WIMP) models can't fully explain without invoking coincidence.
The development of ADM models explores potential symmetries between VM and DM sectors, proposing that the DM asymmetry arose from similar processes that generated the baryon asymmetry. By establishing a correlation between DM and VM asymmetries, the models can account for the concurrent relic densities. A crucial aspect reviewed includes different asymmetry generation mechanisms such as out-of-equilibrium decays, Affleck-Dine dynamics, phase transitions, and asymmetric freeze-out mechanisms, each providing distinct pathways for asymmetry development and its interaction with cosmological phenomena.
The model structures considered extend from simplified scenarios involving minimal particle content to cases involving complex hidden sectors with additional forces and interactions. Notably, the potential for ADM to couple to additional particles in a dark sector or directly with SM particles invites intriguing phenomenological opportunities and experimental scrutiny.
Highlighting significant cosmological and astrophysical implications, the paper examines several consequences of ADM models:
- Cosmological and Astrophysical Bounds: The model suggests possible extra radiation from dark sectors, constrained yet permissible within current measurements of the cosmic microwave background and primordial nucleosynthesis. The existence of self-interacting DM could address small-scale galactic structure formation challenges present in the collisionless cold dark matter paradigm.
- Direct Detection Considerations: Differential cross-sections for DM-nucleon interactions are classified into short-range and long-range, with recent experimental results fueling debates over potential ADM interpretations. Long-range effects significantly reinterpret the results from lower threshold experiments like DAMA and CoGeNT.
- Indirect Detection Viability: ADM diverges from predictions of conventional DM annihilation signals, with the particle-antiparticle annihilation rate suppressed. Induced nucleon decay or late-time processes like bound-state formation presented potential indirect detection pathways.
- Collider and Gravitational Constraints: Collider experiments could search for mediators through their invisible decay widths, presenting a measurable geometry in the form of potential excess from predicted observables. Furthermore, gravitational interactions with ADM, like capture in stellar objects, offer stringent bounds, particularly through gravitational collapse scenarios and effects on stellar dynamics.
The paper draws attention to the broader landscape of ADM models, arguing that even though ADM needs no self-annihilation to keep the symmetric part in check, the complexity allows for various detector signals and astrophysical observations providing potential evidence. Ultimately, as ADM stands at the intersection of particle physics, cosmology, and astrophysics, it presents a compelling alternative framework for explaining dark matter. Yet, realization demands both detailed theoretical models and precise experimental strategies to probe the nature, interactions, and ultimate implications of ADM in the universe's composition.