We present results of the search for sub-GeV 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 years, with a total exposure of 172.9 kg-year. The derived 90% confidence level upper limits exclude a DM-electron scattering cross section above 6.4 × 10−33 cm2 for a DM mass of 0.25 GeV, assuming a light mediator; and above 3.4 × 10−37 cm2 for a 0.4 GeV DM, 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.
@article{arxiv.2510.01927,
title = {Constraints on sub-GeV dark matter scattering on electrons with COSINE-100},
author = {N. Carlin and J. Y. Cho and S. J. Cho and S. Choi and A. C. Ezeribe and L. E. Franca and O. Gileva and C. Ha and I. S. Hahn and S. J. Hollick and E. J. Jeon and H. W. Joo and W. G. Kang and M. Kauer and B. H. Kim and D. Y. Kim and H. J. Kim and J. Kim and K. W. Kim and S. H. Kim and S. K. Kim and W. K. Kim and Y. D. Kim and Y. H. Kim and B. R. Ko and Y. J. Ko and D. H. Lee and E. K. Lee and H. Lee and H. S. Lee and H. Y. Lee and I. S. Lee and J. Lee and J. Y. Lee and M. H. Lee and S. H. Lee and S. M. Lee and Y. J. Lee and D. S. Leonard and N. T. Luan and V. H. A. Machado and B. B. Manzato and R. H. Maruyama and S. L. Olsen and H. K. Park and H. S. Park and J. C. Park and J. S. Park and K. S. Park and K. Park and S. D. Park and R. L. C. Pitta and H. Prihtiadi and S. J. Ra and C. Rott and K. A. Shin and D. F. F. S. Cavalcante and M. K. Son and N. J. C. Spooner and L. T. Truc and L. Yang and G. H. Yu},
journal= {arXiv preprint arXiv:2510.01927},
year = {2026}
}