New Dissipation Mechanisms from Multi-level Dark Matter Scattering

Understand

Multi-level dark matter with diagonal and off-diagonal interactions shows a rich phenomenology in its self-scattering.

• If the interactions are mediated by a particle that is less massive than the dark matter, Sommerfeld effect can lead to resonant enhancement of the scattering.
• For mediators lighter than the level separation, dark matter particles can upscatter to excited states and de-excite by emitting these mediators.
• We compute these cross-sections, both above and below the kinematic threshold, in a generic two-component dark matter model and identify the large inelastic cross-section as a result of maximal mixing between the two states.