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1. Hybrid Simulations of the Resonant and Non-Resonant Cosmic Ray Streaming Instability

   Haggerty, C.; Caprioli, D.; Zweibel, E. (July 2019, 36th International Cosmic Ray Conference (ICRC2019))

   Using hybrid simulations (kinetic ions--fluid electrons), we test the linear theory predictions of the cosmic ray (CR) streaming instability. We consider two types of CR distribution functions: a "hot" distribution where CRs are represented by a drifting power law in momentum and an anisotropic "beam" of monochromatic particles. Additionally, for each CR distribution we scan over different CR densities to transition from triggering the resonant to the non-resonant (Bell) streaming instability. We determine the growth rates of these instabilities in simulations by fitting an exponential curve during the linear stage, and we show that they agree well with the theoretical predictions as a function of wave number agree. We also examine the magnetic helicity as a function of time and wave number, finding a general good agreement with the predictions, as well as some unexpected non-linear features to the instability development. 

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2. Super-resonant dark matter

   https://doi.org/10.1007/JHEP11(2022)162  

   Csáki, Csaba; Gomes, Andrew; Hochberg, Yonit; Kuflik, Eric; Langhoff, Kevin; Murayama, Hitoshi (November 2022, Journal of High Energy Physics)

   A bstract We introduce Super-Resonant Dark Matter , a model of self-interacting dark matter based on the low energy effective theory of supersymmetric QCD. The structure of the theory ensures a resonant enhancement of the self-interactions of the low energy mesons, since their mass ratio is set by the number of colors and flavors. The velocity dependence of the resonantly enhanced self-interactions allows such theories to accommodate puzzles in small scale structure that arise from dark matter halos of different sizes. The dark matter mass is then predicted to be around 3–4 MeV, with its abundance set by freeze-in via a kinetically mixed dark photon. 

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3. Properties and principles of resonant optical lattices

   https://doi.org/10.1109/RAPID54472.2022.9911562  

   Magnusson, Robert; Ko, Yeong Hwan; Razmjooei, Nasrin; Lee, Kyu Jin; Abdullah Simlan, Fairooz; Chen, Ren-Jie; Buchanan-Vega, Joseph; Bootpakdeetam, Pawarat; Gupta, Neelam (September 2022, IEEE)
4. Non-resonant relaxation of rotating globular clusters

   https://doi.org/10.1051/0004-6361/202449465  

   Tep, Kerwann; Fouvry, Jean-Baptiste; Pichon, Christophe (September 2024, Astronomy & Astrophysics)

   The long-term relaxation of rotating, spherically symmetric globular clusters is investigated through an extension of the orbit-averaged Chandrasekhar non-resonant formalism. A comparison is made with the long-term evolution of the distribution function in action space, measured from averages of sets ofN-body simulations up to core collapse. The impact of rotation on in-plane relaxation is found to be weak. In addition, we observe a clear match between theoretical predictions andN-body measurements. For the class of rotating models considered, we find no strong gravo-gyro catastrophe accelerating core collapse. Both kinetic theory and simulations predict a reshuffling of orbital inclinations from overpopulated regions to underpopulated ones. This trend accelerates as the amount of rotation is increased. Yet, for orbits closer to the rotational plane, the non-resonant prediction does not reproduce numerical measurements. We argue that this mismatch stems from these orbits’ coherent interactions, which are not captured by the non-resonant formalism that only addresses local deflections. 

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5. Resonant band engineering of ferroelectric tunnel junctions

   https://doi.org/10.1103/PhysRevB.104.L060101  

   Su, Jing; Zheng, Xingwen; Wen, Zheng; Li, Tao; Xie, Shijie; Rabe, Karin M.; Liu, Xiaohui; Tsymbal, Evgeny Y. (August 2021, Physical Review B)