We highlight a new connection between the Standard Model hierarchy problem and the dark matter sector. The key piece is the relaxion field, which besides scanning the Higgs mass and setting the electroweak scale, also constitutes the observed dark matter abundance of the universe. The relaxation mechanism is realized during inflation, and the necessary friction is provided by particle production. Using this framework we show that the relaxion is a phenomenologically viable dark matter candidate in the keV mass range.

11 pages, 2 figures, 1 table; v2: extended discussion, parameter space includes larger masses and higher reheating temperatures than in v1, matches version accepted by PRD; v3: numerical error corrected, table and figures updated, conclusions unchanged