Influence of Cosmic-Ray Spectrum and Hadron—Nucleus Interaction Model on the Properties of High-Energy Atmospheric-Neutrino Fluxes

Abstract

The neutrino/antineutrino flux ratios (\({\nu _e}/{\overline \nu _e}\) and \({\nu _\mu }/{\overline \nu _\mu }\)) and the flavor ratio \(\left( {{\nu _\mu } + {{\overline \nu }_\mu }} \right)/\left( {{\nu _e} + {{\overline \nu }_e}} \right)\) clearly demonstrate the distinctions between the predictions of hadronic-interaction models for the production spectra of pions and kaons, which are the main sources of atmospheric neutrinos in the region of E_ν ≲ 500 TeV. The values of the \({\nu /\overline \nu }\) ratio are sensitive to variations in the π⁺/π⁻, π/K, and K⁺/K⁻ meson ratios, which are determined by the cross sections for inclusive meson-production processes in hadron-nucleus (hA) collisions; the elemental composition of cosmic rays also exerts influence, through the p/n ratio, on the development of hadronic cascades and on the neutrino ratios. The difference in \({\nu /\overline \nu }\) and in the flavor ratio for a number of hadronic-interaction models is shown on the basis of calculating neutrino fluxes at energies in the range between 10² and 10⁸ GeV. A comparison of the calculated results with new experimental data shows the reliability of this calculation, which, on the whole, reflects correctly the mechanism of atmospheric-neutrino production. The spectra of atmospheric muon neutrinos from calculations based on the Kimel-Mokhov, SIBYLL 2. 1, and EPOS LHC models describe fairly well experimental results. At energies in the range of 1–500 TeV, the curves calculated within these models combined with the Hillas-Gaisser spectrum are close to the best fit to data from measurements in the IceCube experiment.