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1. Properties of Cosmic Deuterons Measured by the Alpha Magnetic Spectrometer

   https://doi.org/10.1103/PhysRevLett.132.261001  

   Aguilar, M; Alpat, B; Ambrosi, G; Anderson, H; Arruda, L; Attig, N; Bagwell, C; Barao, F; Barbanera, M; Barrin, L; et al (June 2024, Physical Review Letters)

   Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of the deuteron ( $D$ ) flux are presented. The measurements are based on $21\times {10}^6$ $D$ nuclei in the rigidity range from 1.9 to 21 GV collected from May 2011 to April 2021. We observe that over the entire rigidity range the $D$ flux exhibits nearly identical time variations with the $p$ , ${}^3\mathrm{He}$ , and ${}^4\mathrm{He}$ fluxes. Above 4.5 GV, the $D/{}^4\mathrm{He}$ flux ratio is time independent and its rigidity dependence is well described by a single power law $\propto R^{\mathrm{\Delta }}$ with ${\mathrm{\Delta }}_{D/{}^4\mathrm{He}}=-0.108\pm 0.005$ . This is in contrast with the ${}^3\mathrm{He}/{}^4\mathrm{He}$ flux ratio for which we find ${\mathrm{\Delta }}_{{}^3\mathrm{He}/{}^4\mathrm{He}}=-0.289\pm 0.003$ . Above $\sim 13\mathrm{GV}$ we find a nearly identical rigidity dependence of the $D$ and $p$ fluxes with a $D/p$ flux ratio of $0.027\pm 0.001$ . These unexpected observations indicate that cosmic deuterons have a sizable primarylike component. With a method independent of cosmic ray propagation, we obtain the primary component of the $D$ flux equal to $9.4\pm 0.5\%$ of the ${}^4\mathrm{He}$ flux and the secondary component of the $D$ flux equal to $58\pm 5\%$ of the ${}^3\mathrm{He}$ flux. Published by the American Physical Society2024 

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2. Properties of Cosmic Lithium Isotopes Measured by the Alpha Magnetic Spectrometer

   https://doi.org/10.1103/PhysRevLett.134.201001  

   Aguilar, M; Ambrosi, G; Anderson, H; Arruda, L; Attig, N; Bagwell, C; Barao, F; Barbanera, M; Barrin, L; Bartoloni, A; et al (May 2025, Physical Review Letters)

   We present the first measurement of cosmic-ray fluxes of ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ isotopes in the rigidity range from 1.9 to 25 GV. The measurements are based on $9.7\times {10}^5$ ${}^6\mathrm{Li}$ and $1.04\times {10}^6$ ${}^7\mathrm{Li}$ nuclei collected by the Alpha Magnetic Spectrometer on the International Space Station from May 2011 to October 2023. We observe that over the entire rigidity range the ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ fluxes exhibit nearly identical time variations and, above $\sim 4\mathrm{GV}$ , the time variations of ${}^6\mathrm{Li}$ , ${}^7\mathrm{Li}$ , He, Be, B, C, N, and O fluxes are identical. Above $\sim 7\mathrm{GV}$ , we find an identical rigidity dependence of the ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ fluxes. This shows that they are both produced by collisions of heavier cosmic-ray nuclei with the interstellar medium and, in particular, excludes the existence of a sizable primary component in the ${}^7\mathrm{Li}$ flux. Published by the American Physical Society2025 

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3. Constraints on $f\left(R\right)$ gravity from thermal-Sunyaev-Zel’dovich-effect-selected SPT galaxy clusters and weak lensing mass calibration from DES and HST

   https://doi.org/10.1103/PhysRevD.111.043519  

   Vogt, S_M L; Bocquet, S; Davies, C T; Mohr, J J; Schmidt, F; Ruan, C-Z; Li, B; Hernández-Aguayo, C; Grandis, S; Bleem, L E; et al (February 2025, Physical Review D)

   We present constraints on the $f\left(R\right)$ gravity model using a sample of 1005 galaxy clusters in the redshift range 0.25–1.78 that have been selected through the thermal Sunyaev-Zel’dovich effect from South Pole Telescope data and subjected to optical and near-infrared confirmation with the multicomponent matched filter algorithm. We employ weak gravitational lensing mass calibration from the Dark Energy Survey Year 3 data for 688 clusters at $z<0.95$ and from the Hubble Space Telescope for 39 clusters with $0.6<z<1.7$ . Our cluster sample is a powerful probe of $f\left(R\right)$ gravity, because this model predicts a scale-dependent enhancement in the growth of structure, which impacts the halo mass function (HMF) at cluster mass scales. To account for these modified gravity effects on the HMF, our analysis employs a semianalytical approach calibrated with numerical simulations. Combining calibrated cluster counts with primary cosmic microwave background temperature and polarization anisotropy measurements from the Planck 2018 release, we derive robust constraints on the $f\left(R\right)$ parameter $f_{R0}$ . Our results, ${\log }_{10}\left|f_{R0}\right|<-5.32$ at the 95% credible level, are the tightest current constraints on $f\left(R\right)$ gravity from cosmological scales. This upper limit rules out $f\left(R\right)$ -like deviations from general relativity that result in more than a $\sim 20\%$ enhancement of the cluster population on mass scales $M_{200\mathrm{c}}>3\times {10}^{14}{M}_{\odot }$ . Published by the American Physical Society2025 

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4. Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector

   https://doi.org/10.1103/PhysRevD.110.082008  

   Kitagawa, H; Tada, T; Abe, K; Bronner, C; Hayato, Y; Hiraide, K; Hosokawa, K; Ieki, K; Ikeda, M; Kameda, J; et al (October 2024, Physical Review D)

   We present the results of the charge ratio ( $R$ ) and polarization ( $P_0^{\mu }$ ) measurements using decay electron events collected between September 2008 and June 2022 with the Super-Kamiokande detector. Because of its underground location and long operation, we are able to perform high-precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be $R=1.32\pm 0.02(\mathrm{stat}+\mathrm{syst})$ at $E_{\mu }\cos {\theta }_{\text{Zenith}}={0.7}_{-0.2}^{+0.3}\mathrm{TeV}$ , where $E_{\mu }$ is the muon energy and ${\theta }_{\text{Zenith}}$ is the zenith angle of incoming cosmic-ray muons. This result is consistent with the Honda flux model while indicating a tension with the $\pi K$ model of $1.9\sigma$ . We also measured the muon polarization at the production location to be $P_0^{\mu }=0.52\pm 0.02(\mathrm{stat}+\mathrm{syst})$ at the muon momentum of ${0.9}_{-0.1}^{+0.6}\mathrm{TeV}/c$ at the surface of the mountain; this also suggests a tension with the Honda flux model of $1.5\sigma$ . This is the most precise measurement ever to experimentally determine the cosmic-ray muon polarization near $1\mathrm{TeV}/c$ . These measurement results are useful to improve atmospheric neutrino simulations. Published by the American Physical Society2024 

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5. Antiprotons and Elementary Particles over a Solar Cycle: Results from the Alpha Magnetic Spectrometer

   https://doi.org/10.1103/PhysRevLett.134.051002  

   Aguilar, M; Ambrosi, G; Anderson, H; Arruda, L; Attig, N; Bagwell, C; Barao, F; Barbanera, M; Barrin, L; Bartoloni, A; et al (February 2025, Physical Review Letters)

   We present results over an 11-year Solar cycle of cosmic antiprotons based on $1.1\times {10}^6$ events in the rigidity range from 1.00 to 41.9 GV. The $\overline{p}$ fluxes exhibit distinct properties. The magnitude of the $\overline{p}$ flux temporal variation is significantly smaller than those of $p$ , $e^{-}$ , and $e^{+}$ . A hysteresis between the $\overline{p}$ fluxes and the $p$ fluxes is observed, whereas the $\overline{p}$ and $e^{-}$ fluxes show a linear correlation. With a model-independent analysis, we found a universal relation between the shape of the rigidity spectrum and the magnitude of flux temporal variation over an 11-year Solar cycle for both positively and negatively charged particles. The simultaneous results on $\overline{p}$ and $p$ , $e^{-}$ , and $e^{+}$ provide unique information for understanding particle transport in the Solar System as a function of mass, charge, and spectral shape. 

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