Constraints on WIMP-like dark matter scattering on electrons with COSINE-100

We present results of the search for WIMP-like dark matter interaction with electrons in the NaI (Tl) crystals of the COSINE-100 experiment. The two benchmark scenarios of a heavy and a light vector boson as mediator of the interaction were studied. We found no excess events over the expected background in a data-set of 2. 82 yr, with a total exposure of 172. 9 kg. yr. The derived 90% confidence level upper limits exclude a WIMP-electron scattering cross section above 6. 4 10^-33 cm² for a WIMP mass of 0. 25 GeV, assuming a light mediator; and above 3. 4 10^-37 cm² for a 0. 4 GeV WIMP, assuming a heavy mediator, and represent the most stringent constraints for a NaI (Tl) target to date. We also briefly discuss a planned analysis using an annual modulation method below the current 0. 7 keV threshold of COSINE-100, down to few photoelectrons yield.