Selection Rule for Enhanced Dark Matter Annihilation.

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• Dark matter annihilation is a key process for understanding dark matter properties.
• The Sommerfeld effect significantly modifies annihilation rates at low velocities.
• Standard models predict velocity-suppressed p-wave annihilation.

Purpose of the Study:

• To identify a selection rule for dark matter annihilation and coannihilation processes.
• To investigate the impact of this rule on odd and even partial waves.
• To explore the potential for p-wave annihilation to dominate dark matter signals.

Main Methods:

• Application of the Sommerfeld effect to dark matter annihilation.
• Analysis of selection rules based on exchange symmetry of identical particles.
• Modeling of multistate dark matter with off-diagonal long-range interactions.

Main Results:

• A selection rule is identified that enhances odd partial waves and suppresses even partial waves.
• P-wave annihilation, typically velocity-suppressed, can become dominant.
• Parametric differences arise between relic and late-time annihilation rates.

Conclusions:

• The identified selection rule offers a new mechanism for dark matter annihilation.
• Distinctive phenomenology with large, velocity-dependent annihilation rates is predicted.
• This provides a novel observable signature for dark matter detection.