Limits on WIMP dark matter with NaI(Tl) crystals in three years of COSINE-100 data

TL;DR

This study reports new limits on low-mass WIMP dark matter using three years of COSINE-100 NaI(Tl) data, significantly constraining the DAMA signal and advancing detection sensitivity in the sub-GeV mass range.

Contribution

The paper presents the first three-year COSINE-100 results with an improved energy threshold of 0.7 keV, providing stronger constraints on WIMP models and challenging the DAMA/LIBRA claim.

Findings

No WIMP excess observed, setting new upper limits.

DAMA signal regions are fully excluded at 3σ.

Enhanced sensitivity to sub-GeV WIMPs via the Migdal effect.

Abstract

We report limits on WIMP dark matter derived from three years of data collected by the COSINE-100 experiment with NaI(Tl) crystals, achieving an improved energy threshold of 0.7 keV. This lowered threshold enhances sensitivity in the sub-GeV mass range, extending the reach for direct detection of low-mass dark matter. Although no excess of WIMP-like events was observed, the increased sensitivity enabled a model-insensitive comparison between the expected WIMP signal rate-based on mass limits from our data-and DAMA's reported modulation amplitude. Our findings strongly disfavor the DAMA signal as originating from WIMP interactions, fully excluding DAMA/LIBRA 3$\sigma$ allowed regions and providing enhanced WIMP mass limits by an order of magnitude in the spin-independent model compared to previous results. In the spin-dependent model, cross-section upper limits were obtained in the mass range [0.1-5.0] GeV/c$^2$, with additional sensitivity to sub-GeV WIMPs through the inclusion of the Migdal effect. These results represent substantial progress in low-mass dark matter exploration and reinforce constraints on the longstanding DAMA claim.