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1. Constraints on metastable superheavy dark matter coupled to sterile neutrinos with the Pierre Auger Observatory

   https://doi.org/10.1103/PhysRevD.109.L081101  

   Abdul_Halim, A; Abreu, P; Aglietta, M; Allekotte, I; Almeida_Cheminant, K; Almela, A; Aloisio, R; Alvarez-Muñiz, J; Ammerman_Yebra, J; Anastasi, G A; et al (April 2024, Physical Review D)

   Dark matter particles could be superheavy, provided their lifetime is much longer than the age of the Universe. Using the sensitivity of the Pierre Auger Observatory to ultrahigh energy neutrinos and photons, we constrain a specific extension of the Standard Model of particle physics that meets the lifetime requirement for a superheavy particle by coupling it to a sector of ultralight sterile neutrinos. Our results show that, for a typical dark coupling constant of 0.1, the mixing angle ${\theta }_m$between active and sterile neutrinos must satisfy, roughly, ${\theta }_m\lesssim 1.5\times {10}^{-6}(M_X/{10}^9\mathrm{GeV}{)}^{-2}$for a mass $M_X$of the dark-matter particle between ${10}^8\mathrm{GeV}$and ${10}^{11}\mathrm{GeV}$. Published by the American Physical Society2024 

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2. Probing superheavy dark matter through lunar radio observations of ultrahigh-energy neutrinos and the impacts of neutrino cascades

   https://doi.org/10.1103/PhysRevD.111.083007  

   Das, Saikat; Carpio, Jose Alonso; Murase, Kohta (April 2025, Physical Review D)

   Ultrahigh-energy neutrinos ( $\mathrm{UHE}\nu$s) can be used as a valuable probe of superheavy dark matter above $\sim {10}^9\mathrm{GeV}$, the latter being difficult to probe with collider and direct detection experiments due to the feebly interacting nature. Searching for radio emissions originating from the interaction of $\mathrm{UHE}\nu$s with the lunar regolith enables us to explore energies beyond ${10}^{12}\mathrm{GeV}$, which astrophysical accelerators cannot achieve. Taking into account the interaction of $\mathrm{UHE}\nu$s with the cosmic neutrino background and resulting standard neutrino cascades to calculate the neutrino flux on Earth, for the first time, we investigate sensitivities of such lunar radio observations to very heavy dark matter. We also examine the impacts of cosmogenic neutrinos that have the astrophysical origin. We show that the proposed ultralong wavelength lunar radio telescope, as well as the existing low-frequency array, can provide the most stringent constraints on decaying or annihilating superheavy dark matter with masses at $\gtrsim {10}^{12}\mathrm{GeV}$. The limits are complementary to or even stronger than those from other $\mathrm{UHE}\nu$detectors, such as the IceCube-Gen2 radio array and the Giant Radio Array for Neutrino Detection. 

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3. Probing Benchmark Models of Hidden-Sector Dark Matter with DAMIC-M

   https://doi.org/10.1103/2tcc-bqck  

   Aggarwal, K; Arnquist, I; Avalos, N; Bertou, X; Castelló-Mor, N; Chavarria, A E; Cuevas-Zepeda, J; Dastgheibi-Fard, A; De_Dominicis, C; Deligny, O; et al (August 2025, Physical Review Letters)

   We report on a search for sub-GeV dark matter (DM) particles interacting with electrons using the DAMIC-M prototype detector at the Modane Underground Laboratory. The data feature a significantly lower detector single $e^{-}$rate (factor 50) compared to our previous search, while also accumulating a 10 times larger exposure of $\sim 1.3\mathrm{kg}\text{−}\mathrm{day}$. DM interactions in the skipper charge-coupled devices (CCDs) are searched for as groups of two or three adjacent pixels with a total charge between 2 and $4e^{-}$. We find 144 candidates of $2e^{-}$and 1 candidate of $4e^{-}$, where 141.5 and 0.071, respectively, are expected from background. With no evidence of a DM signal, we place stringent constraints on DM particles with masses between 1 and $1000\mathrm{MeV}/c^2$interacting with electrons through an ultralight or heavy mediator. For large ranges of DM masses below $1\mathrm{GeV}/c^2$, we exclude theoretically motivated benchmark scenarios where hidden-sector particles are produced as a major component of DM in the Universe through the freeze-in or freeze-out mechanisms. 

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4. First Search for Dark-Trident Processes Using the MicroBooNE Detector

   https://doi.org/10.1103/PhysRevLett.132.241801  

   Abratenko, P; Alterkait, O; Andrade_Aldana, D; Arellano, L; Asaadi, J; Ashkenazi, A; Balasubramanian, S; Baller, B; Barr, G; Barrow, D; et al (June 2024, Physical Review Letters)

   We present a first search for dark-trident scattering in a neutrino beam using a dataset corresponding to $7.2\times {10}^{20}$protons on target taken with the MicroBooNE detector at Fermilab. Proton interactions in the neutrino target at the main injector produce ${\pi }^0$and $\eta$mesons, which could decay into dark-matter (DM) particles mediated via a dark photon $A^{\prime }$. A convolutional neural network is trained to identify interactions of the DM particles in the liquid-argon time projection chamber (LArTPC) exploiting its imagelike reconstruction capability. In the absence of a DM signal, we provide limits at the 90% confidence level on the squared kinematic mixing parameter ${ϵ}^2$as a function of the dark-photon mass in the range $10\le M_{A^{\prime }}\le 400\mathrm{MeV}$. The limits cover previously unconstrained parameter space for the production of fermion or scalar DM particles $\chi$for two benchmark models with mass ratios $M_{\chi }/M_{A^{\prime }}=0.6$and 2 and for dark fine-structure constants $0.1\le {\alpha }_D\le 1$. Published by the American Physical Society2024 

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5. Dark dimension, the swampland, and the dark matter fraction composed of primordial near-extremal black holes

   https://doi.org/10.1103/PhysRevD.109.095008  

   Anchordoqui, Luis A; Antoniadis, Ignatios; Lüst, Dieter (May 2024, Physical Review D)

   In a recent publication we studied the decay rate of primordial black holes perceiving the dark dimension, an innovative five-dimensional (5D) scenario that has a compact space with characteristic length scale in the micron range. We demonstrated that the rate of Hawking radiation of 5D black holes slows down compared to 4D black holes of the same mass. Armed with our findings we showed that for a species scale of $\mathcal{O}\left({10}^{10}\mathrm{GeV}\right)$, an all-dark-matter interpretation in terms of primordial black holes should be feasible for black hole masses in the range ${10}^{14}\lesssim M/\mathrm{g}\lesssim {10}^{21}$. As a natural outgrowth of our recent study, herein we calculate the Hawking evaporation of near-extremal 5D black holes. Using generic entropy arguments we demonstrate that Hawking evaporation of higher-dimensional near-extremal black holes proceeds at a slower rate than the corresponding Schwarzschild black holes of the same mass. Assisted by this result we show that if there were 5D primordial near-extremal black holes in nature, then a primordial black hole all-dark-matter interpretation would be possible in the mass range ${10}^5\sqrt{\beta }\lesssim M/\mathrm{g}\lesssim {10}^{21}$, where $\beta$is a parameter that controls the difference between mass and charge of the associated near-extremal black hole. Published by the American Physical Society2024 

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