Scalar singlet dark matter in non-standard cosmologies

Area of Science:

• Cosmology
• Particle Physics
• Dark Matter Physics

Background:

• The Standard Model of particle physics does not account for dark matter (DM), a major component of the universe.
• Scalar singlet particles interacting via the Higgs portal are a viable dark matter candidate.
• Cosmic expansion history is typically assumed to be standard, potentially overlooking crucial cosmological effects.

Purpose of the Study:

• To investigate dark matter production mechanisms (freeze-out and freeze-in) within models featuring a non-standard cosmic expansion.
• To analyze how variations in the expansion history affect dark matter abundance and its observable consequences.
• To explore the implications for dark matter properties, such as portal coupling strengths and direct detection prospects.

Main Methods:

• Utilizing theoretical modeling of dark matter production in cosmological scenarios with non-standard expansion phases.
• Analyzing both freeze-out and freeze-in production mechanisms for scalar singlet dark matter.
• Evaluating constraints from cosmological observations and particle physics experiments.
• Assessing the impact of non-standard expansion on Higgs portal couplings.

Main Results:

• A non-standard expansion phase significantly alters the predicted dark matter abundance.
• For dark matter freeze-in, a much larger Higgs portal coupling is required.
• For dark matter freeze-out, significantly smaller Higgs portal couplings become permissible.
• The required dark matter properties are sensitive to the cosmic expansion history.

Conclusions:

• Non-standard cosmic expansion models offer new possibilities for dark matter particle physics.
• Altered expansion histories can reconcile dark matter observations with different parameter spaces.
• These findings highlight the importance of considering cosmological effects in dark matter searches and direct detection experiments.