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1. DarkSide-20k sensitivity to light dark matter particles

   https://doi.org/10.1038/s42005-024-01896-z  

   Acerbi, F; Adhikari, P; Agnes, P; Ahmad, I; Albergo, S; Albuquerque, I_F M; Alexander, T; Alton, A K; Amaudruz, P; Angiolilli, M; et al (December 2024, Communications Physics)

   The dual-phase liquid argon time projection chamber is presently one of the leading technologies to search for dark matter particles with masses below 10 GeV c−2. This was demonstrated by the DarkSide-50 experiment with approximately 50 kg of low-radioactivity liquid argon as target material. The next generation experiment DarkSide-20k, currently under construction, will use 1,000 times more argon and is expected to start operation in 2027. Based on the DarkSide-50 experience, here we assess the DarkSide-20k sensitivity to models predicting light dark matter particles, including Weakly Interacting Massive Particles (WIMPs) and sub-GeV c−2 particles interacting with electrons in argon atoms. With one year of data, a sensitivity improvement to dark matter interaction cross-sections by at least one order of magnitude with respect to DarkSide-50 is expected for all these models. A sensitivity to WIMP–nucleon interaction cross-sections below 1 × 10−42 cm2 is achievable for WIMP masses above 800 MeV c−2. With 10 years exposure, the neutrino fog can be reached for WIMP masses around 5 GeV c−2. 

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2. Search for charged excited states of dark matter with KamLAND-Zen

   https://doi.org/10.1016/j.physletb.2024.138846  

   Abe, S; Eizuka, M; Futagi, S; Gando, A; Gando, Y; Goto, S; Hachiya, T; Hata, K; Hosokawa, K; Ichimura, K; et al (August 2024, Physics Letters B)

   Particle dark matter could belong to a multiplet that includes an electrically charged state. WIMP dark matter (χ0) accompanied by a negatively charged excited state (χ−) with a small mass difference (e.g. < 20 MeV) can form a bound-state with a nucleus such as xenon. This bound-state formation is rare and the released energy is O(1−10) MeV depending on the nucleus, making large liquid scintillator detectors suitable for detection. We searched for bound-state formation events with xenon in two experimental phases of the KamLAND-Zen experiment, a xenon-doped liquid scintillator detector. No statistically significant events were observed. For a benchmark parameter set of WIMP mass mχ0=1 TeV and mass difference Δm=17 MeV, we set the most stringent upper limits on the recombination cross section times velocity 〈σv〉 and the decay-width of χ− to 9.2×10−30cm3/s and 8.7×10−14 GeV, respectively at 90% confidence level. 

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3. Search for dark matter from the centre of the Earth with 8 years of IceCube data

   https://doi.org/10.1088/1748-0221/16/11/C11012  

   Renzi, G. (November 2021, Journal of Instrumentation)

   Abstract Neutrinos have been proved to be unique messengers in the understanding of fundamental physics processes, and in astrophysical data sets they may provide hints of physics beyond the Standard Model. For example, neutrinos could be the key to discerning between various dark matter models that are based on Weakly Interacting Massive Particles (WIMPs). WIMPs can scatter off standard matter nuclei in the vicinity of massive bodies such as the Sun or the Earth, lose velocity, and be gravitationally trapped in the center of the body. Self-annihilation of dark matter into Standard Model particles may produce an observable flux of neutrinos. For the case of the Earth, an excess of neutrinos coming from the center of the planet could indicate WIMP capture and annihilation at the Earth’s core. The IceCube Neutrino Observatory, located at the geographical South Pole, is sensitive to these excess neutrinos. A search has been conducted on 8 years of IceCube data, probing multiple dark matter channels and masses. With this analysis, we show that IceCube has world-leading sensitivity to the spin-independent dark matter-nucleon scattering cross section above a WIMP mass of 100 GeV. 

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4. The XENONnT dark matter experiment

   https://doi.org/10.1140/epjc/s10052-024-12982-5  

   XENON_Collaboration; Aprile, E.; Aalbers, J.; Abe, K.; Ahmed_Maouloud, S.; Althueser, L.; Andrieu, B.; Angelino, E.; Angevaare, J_R; Antochi, V_C; et al (August 2024, The European Physical Journal C)

   Abstract The multi-staged XENON program at INFN Laboratori Nazionali del Gran Sasso aims to detect dark matter with two-phase liquid xenon time projection chambers of increasing size and sensitivity. The XENONnT experiment is the latest detector in the program, planned to be an upgrade of its predecessor XENON1T. It features an active target of 5.9 tonnes of cryogenic liquid xenon (8.5 tonnes total mass in cryostat). The experiment is expected to extend the sensitivity to WIMP dark matter by more than an order of magnitude compared to XENON1T, thanks to the larger active mass and the significantly reduced background, improved by novel systems such as a radon removal plant and a neutron veto. This article describes the XENONnT experiment and its sub-systems in detail and reports on the detector performance during the first science run. 

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5. Enhancing direct detection of Higgsino dark matter

   https://doi.org/10.1103/PhysRevD.111.055030  

   Graham, Peter W; Ramani, Harikrishnan; Wong, Samuel_S Y (March 2025, Physical Review D)

   While much supersymmetric weakly interacting massive particle (WIMP) parameter space has been ruled out, one remaining important candidate is Higgsino dark matter. The Higgsino can naturally realize the “inelastic dark matter” scenario, where the scattering off a nucleus occurs between two nearly-degenerate states, making it invisible to WIMP direct detection experiments if the splitting is too large to be excited. It was realized that a “luminous dark matter” detection process, where the Higgsino upscatters in the Earth and subsequently decays into a photon in a large neutrino detector, offers the best sensitivity to such a scenario. We consider the possibility of adding a large volume of a heavy element, such as Pb or U, around the detector. We also consider the presence of U and Th in the Earth itself, and the effect of an enhanced high-velocity tail of the dark matter distribution due to the presence of the Large Magellanic Cloud. These effects can significantly improve the sensitivity of detectors such as JUNO, $\mathrm{SNO}+$, KamLAND, and Borexino, potentially making it possible in the future to cover much of the remaining parameter space for this classic supersymmetric WIMP dark matter. Published by the American Physical Society2025 

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