Speaker
Description
We report new constraints on the spin-dependent (SD) dark matter (DM)-proton cross section using the COSINE-100 experiment at the Yangyang Underground Laboratory.
By implementing a specialized event selection including Multi-Layer Perceptron (MLP) training, this analysis achieves a detection threshold of 3- and 4-pulse clusters corresponding to the few photoelectrons. This allows us to access the unstudied few-photoelectron regime, significantly below the previous 8-photoelectron threshold.
Using four years of stable data, we find no statistically significant evidence of annual modulation. Consequently, we establish the world's most stringent SD DM-proton constraints for NaI(Tl) in the $1.75–2.25$ GeV/$c^2$ mass range. By incorporating the Migdal effect, we further extend our sensitivity into the $15–58$ MeV/$c^2$ mass range, setting new world-leading limits. These results demonstrate the unique capability of NaI(Tl) targets to probe previously unexplored regions of the dark matter parameter space.
| Main Contribution topic | Direct detection |
|---|---|
| Secondary contribution topic | Light Dark Matter |