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   Sokół, Justyna M.; Kucharek, Harald; Baliukin, Igor I.; Fahr, Hans; Izmodenov, Vladislav V.; Kornbleuth, Marc; Mostafavi, Parisa; Opher, Merav; Park, Jeewoo; Pogorelov, Nikolai V.; et al (April 2022, Space Science Reviews)

   Abstract Interstellar neutrals (ISNs), pick-up ions (PUIs), and energetic neutral atoms (ENAs) are fundamental constituents of the heliosphere and its interaction with the neighboring interstellar medium. Here, we focus on selected aspects of present-day theory and modeling of these particles. In the last decades, progress in the understanding of the role of PUIs and ENAs for the global heliosphere and its interaction with very local interstellar medium is impressive and still growing. The increasing number of measurements allows for verification and continuing development of the theories and model attempts. We present an overview of various model descriptions of the heliosphere and the processes throughout it including the kinetic, fluid, and hybrid solutions. We also discuss topics in which interplay between theory, models, and interpretation of measurements reveals the complexity of the heliosphere and its understanding. They include model-based interpretation of the ISN, PUI, and ENA measurements conducted from the Earth’s vicinity. In addition, we describe selected processes beyond the Earth’s orbit up to the heliosphere boundary regions, where PUIs significantly contribute to the complex system of the global heliosphere and its interaction with the VLISM. 

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3. Neutral-current neutrino scattering from the deuteron

   https://doi.org/10.1103/PhysRevC.101.064621  

   Jeschonnek, Sabine; Van Orden, J. W.; Donnelly, T. W. (June 2020, Physical Review C)

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4. Precision measurement of the neutral pion lifetime

   https://doi.org/10.1126/science.aay6641  

   Larin, I.; Zhang, Y.; Gasparian, A.; Gan, L.; Miskimen, R.; Khandaker, M.; Dale, D.; Danagoulian, S.; Pasyuk, E.; Gao, H.; et al (April 2020, Science)

   The explicit breaking of the axial symmetry by quantum fluctuations gives rise to the so-called axial anomaly. This phenomenon is solely responsible for the decay of the neutral pion π⁰into two photons (γγ), leading to its unusually short lifetime. We precisely measured the decay width Γ of the ${\pi }^0\to \gamma \gamma$process. The differential cross sections for π⁰photoproduction at forward angles were measured on two targets, carbon-12 and silicon-28, yielding $\mathrm{\Gamma }\left({\pi }^0\to \gamma \gamma \right)=7.798\pm 0.056\left(\mathrm{stat}\mathrm{.}\right)\pm 0.109\left(\mathrm{syst}\mathrm{.}\right)\mathrm{ eV}$, where stat. denotes the statistical uncertainty and syst. the systematic uncertainty. We combined the results of this and an earlier experiment to generate a weighted average of $\mathrm{\Gamma }\left({\pi }^0\to \gamma \gamma \right)=7.802\pm 0.052\left(\mathrm{stat}\mathrm{.}\right)\pm 0.105\left(\mathrm{syst}\mathrm{.}\right)\mathrm{ eV}$. Our final result has a total uncertainty of 1.50% and confirms the prediction based on the chiral anomaly in quantum chromodynamics. 

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5. The Neutral ISM of the Extremely Metal­Deficient Galaxy Leoncino

   Bartz, Josh; Page, Tylyn; Cannon, John M.; Adams, Elizabeth; Berg, Danielle; Dolphin, Andrew; Giovanelli, Riccardo; Gordon, Alex J.; Haynes, Martha P.; Hirschauer, Alec S.; et al (January 2019, American Astronomical Society, AAS Meeting)

   We present new multi-configuration VLA HI spectral line imaging of the dwarf galaxies AGC 198691 (hereafter, Leoncino) and UGC 5186. Leoncino is one of 82 galaxies in the "Survey of HI in Extremely Low-mass Dwarfs" ("SHIELD"), a multi-wavelength investigation of low-mass galaxies that were cataloged by the Arecibo Legacy Fast ALFA (ALFALFA) survey. Leoncino is one of the lowest metallicity galaxies known in the local universe (Hirschauer et al. 2016). A single pointing with the VLA allows us to study the HI morphology and dynamics of both galaxies simultaneously. We present HI images at a variety of angular resolutions in order to explore both the global and the resolved properties of the neutral ISM. 

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