Heavy Thermal Dark Matter from a New Collision Mechanism.

Area of Science:

• Cosmology
• Particle Physics
• Astrophysics

Background:

• The nature of dark matter remains one of the most significant unsolved problems in cosmology.
• Existing dark matter models often face constraints from unitarity bounds and observational data.
• Standard thermal freeze-out mechanisms typically predict dark matter masses within a limited range.

Purpose of the Study:

• To propose a new thermal freeze-out mechanism for dark matter production.
• To explore the possibility of dark matter masses exceeding conventional unitarity bounds.
• To demonstrate this mechanism within a specific theoretical framework, such as a leptophilic dark matter model.

Main Methods:

• Introducing a novel thermal freeze-out process: χζ^{†}→ζζ, where χ is the dark matter candidate.
• Analyzing the relic abundance determination through this scattering process.
• Investigating the conditions m_{ζ}
• Demonstrating the mechanism in a leptophilic dark matter model.

Main Results:

• The proposed mechanism allows dark matter masses to exceed the unitarity bound by many orders of magnitude.
• Perturbative unitarity and standard cosmology remain unmodified.
• The process enables exponentially heavier dark matter for a given interaction strength compared to 2→2 freeze-out.
• Dark matter masses up to 10^9 GeV are achievable within the demonstrated leptophilic model.

Conclusions:

• The novel thermal freeze-out mechanism provides a viable pathway for producing very heavy dark matter candidates.
• This mechanism reconciles the existence of super-heavy dark matter with fundamental physics principles and standard cosmology.
• The demonstrated leptophilic model showcases the broad applicability and potential of this new freeze-out scenario.