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

We set the strongest limits to date on the velocity-independent dark matter (DM)-proton cross section sigma 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 sigma < 6 x 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 arc improved by up to a factor of 25.

Automated summary

This study sets the strongest limits to date on the velocity-independent dark matter-proton cross section using large-scale structure traced by the Lyman-alpha forest. The research uses an emulator of cosmological simulations and data from the smallest cosmological scales to model and search for the imprint of primordial dark matter-proton collisions, improving cosmological bounds by up to a factor of 25.