Uncertainties in Atmospheric Muon-Neutrino Fluxes Arising from Cosmic-Ray Primaries
Abstract
We present an updated calculation of the uncertainties on the atmospheric muon-neutrino flux arising from cosmic-ray primaries. For the first time, we include recent measurements of the cosmic-ray primaries collected since 2005. We apply a statistical technique that allows the determination of correlations between the parameters of the GSHL primary-flux parametrisation and the incorporation of these correlations into the uncertainty on the muon-neutrino flux. We obtain an uncertainty related to the primary cosmic rays of around (5--15)\%, depending on energy, which is about a factor of two smaller than the previously determined uncertainty. The hadron production uncertainty is added in quadrature to obtain the total uncertainty on the neutrino flux, which is reduced by ≈ 5\%. To take into account an unexpected hardening of the spectrum of primaries above energies of 100 GeV observed in recent measurements, we propose an alternative parametrisation and discuss its impact on the neutrino flux uncertainties.