If dark matter was produced in the early Universe by the decoupling of its annihilations into known particles, there is a sharp experimental target for the size of its coupling. We show that if dark matter was produced by inelastic scattering against a lighter particle from the thermal bath, then its coupling can be exponentially smaller than the coupling required for its production from annihilations. As an application, we demonstrate that dark matter produced by inelastic scattering against electrons provides new thermal relic targets for direct detection and fixed target experiments.

• Received 26 June 2019
• Revised 16 January 2020
• Accepted 12 March 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.151801

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Published by the American Physical Society