Recently the AMS-02 collaboration has published the measurement of the cosmic antiproton to proton ratio ¯ p/p and the ¯ p flux with a high precision up to ∼ 450 GeV. In this work, we perform a systematic analysis of the secondary antiproton flux generated by the cosmic ray interaction with the interstellar gas. The uncertainty of the prediction originates from the cosmic ray propagation process and the hadronic interaction models. Although the cosmic ray propagation parameters have been well controlled by the AMS-02 B/C ratio data for a specified model, different propagation models can not be discriminated by the B/C data. The ¯ p flux is also calculated for several hadronic interaction models, which are generally adopted by the cosmic ray community. However, the results for different hadronic models do not converge. We find the EPOS LHC model, which seems to fit the collider data very well, predicts a slightly lower ¯ p/p ratio than the AMS-02 data at the high energy end. Finally we derive the constraints on the dark matter annihilation cross section from the AMS-02 ¯ p/p ratio for different propagation and hadronic interaction models. PACS numbers: 96.50.S-,95.35.+d

We report new measurements of the muon spectra and the muon charge ratio at ground level in the momentum range from 200 MeV͞c to 120 GeV͞c for two different geomagnetic locations. Above 0.9 GeV͞c the absolute spectra measured in the two locations are in good agreement and are about 10% to 15% lower than previous experimental results. At lower momenta the data show latitude dependent geomagnetic effects. These observations are important for the understanding of the observed neutrino anomaly. PACS numbers: 96.40.Tv, 96.40.Kk, 14.60.PqPrecise measurements of the muon energy spectrum and charge ratio at sea level over a wide energy range provide information on the propagation of cosmic rays in the atmosphere. Together with data on the primary cosmic rays, muon measurements can be used as a test to check calculations of atmospheric cascades and neutrino fluxes [1]. These latter calculations are used to interpret the recent re-

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A new measurement of the primary cosmic-ray proton and helium fluxes from 3 to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998. This experimental setup combines different detector techniques and has excellent particle discrimination capabilities allowing clear particle identification. Our experiment has the capability to determine accurately detector selection efficiencies and systematic errors associated with them. Furthermore, it can check for the first time the energy determined by the magnet spectrometer by using the Cherenkov angle measured by the RICH detector well above 20 GeV/n. The analysis of the primary proton and helium components is described here and the results are compared with other recent measurements using other magnet spectrometers. The observed energy spectra at the top of the atmosphere can be represented by (1.27±0.09) × 10 4 E −2.75±0.02 particles (m 2 GeV sr s) −1 , where E is the kinetic energy, for protons between 20 and 350 GeV and (4.8±0.8) × 10 2 E −2.67±0.06 particles (m 2 GeV nucleon −1 sr s) −1 , where E is the kinetic energy per nucleon, for helium nuclei between 15 and 150 GeV nucleon −1 .