Search for solar bosonic dark matter annual modulation with COSINE-100

We present results from a search for solar bosonic dark matter using the annual modulation method with the COSINE-100 experiment. The results were interpreted considering three dark sector bosons models: solar dark photons, Dine-Fischler-Srednicki-Zhitnisky (DFSZ) and Kim-Shifman-Vainshtein-Zakharov (KSVZ) solar axions, and Kaluza-Klein solar axions. No modulation signal compatible with the expected from the models was found from a dataset of 2.82 yr, using 61.3 kg of NaI(Tl) crystals. Therefore, we set a 90% confidence level upper limits for each of the three models studied. For the solar dark photon model, the most stringent mixing parameter upper limit is 1.61×10-14 for dark photons with a mass of 215 eV. For the DFSZ and KSVZ solar axion, and the Kaluza-Klein axion models, the upper limits exclude axion-electron couplings, gae, above 1.61×10-11 for axion mass below 0.2 keV; and axion-photon couplings, gaγγ, above 1.83×10-11 GeV-1 for an axion number density of 4.07×1013 cm-3. This is the first experimental search for solar dark photons and DFSZ and KSVZ solar axions using the annual modulation method. The lower background, higher light yield and reduced threshold of NaI(Tl) crystals of the future COSINE-200 experiment are expected to enhance the sensitivity of the analysis shown in this paper. We show the sensitivities for the three models studied, considering the same search method with COSINE-200.