ИСТИНА

High-energy neutrinos arising from decays of the cosmic ray-induced hadrons in the Earth’s atmosphere form the background flux for astrophysical neutrinos. The problem of the atmospheric neutrino background is really important after detection in IceCube experiment of several tens events from extraterrestrial neutrinos with energies up to 4 PeV. We calculate the atmospheric neutrino spectra in the energy range of 100 GeV - 100 PeV using the set of the hadronic models and several parametrizations of cosmic ray spectra supported by experimental data. Above 100 TeV calculated spectra of muon neutrinos show the apparent dependence on the spectrum and composition of primary cosmic rays around to the knee. Also in this energy range uncertainties appear due to production cross sections and decays of the charmed particles which imprint on the prompt neutrino flux. Basing on this calculation we display the influence of the cosmic-ray spectrum and composition on the neutrino to antineutrino flux ratio as well the neutrino flavor ratio. These neutrino flux characteristics are sensitive to meson charge ratios as well to π/K yield, which depend not only on cross-sections for hA-collisions but also on the the cosmic-ray composition due to p/n ratio induced by elemental composition of cosmic rays. Comparative analysis of atmospheric neutrino fluxes, calculated in framework of the two methods Z(E, h) functions approach and the Matrix Cascade Equations method (MCEq), demonstrates the close agreement of both calculations in the spectra shape and values. It is shown that rare decays of shortlived neutral каоns contribute about a third of the conventional νe flux at the energies above 100 ТeV. Calculated neutrino spectra agree rather well with the measurement data of IceCube and ANTARES experiments. Uncertainties of the experimental data above 500 TeV leave a window for the prompt neutrino component predicted with use of the quark-qluon string model (QGSM).