Limits on the Light Dark Matter–Proton Cross Section from Cosmic Large-Scale Structure

• DOI: 10.1103/physrevlett.128.171301
• Publication Date: 2022-04-27T14:06:39Z
• Authors: Keir K. Rogers; Cora Dvorkin; Hiranya V. Peiris
• Keywords: 13. Climate action; astro-ph.CO; hep-ph

We set the strongest limits to date on the velocity-independent dark matter (DM)-proton cross section σ for DM masses m=10 keV to 100 GeV, using large-scale structure traced by the Lyman-alpha forest: e.g., a 95% lower limit σ<6×10^{-30} cm^{2}, for m=100 keV. Our results complement direct detection, which has limited sensitivity to sub-GeV DM. We use an emulator of cosmological simulations, combined with data from the smallest cosmological scales used to date, to model and search for the imprint of primordial DM-proton collisions. Cosmological bounds are improved by up to a factor of 25.