Atmospheric Lepton Fluxes

TL;DR

This review analyzes atmospheric muon and neutrino fluxes at high energies, discussing their features, the impact of cosmic-ray spectrum uncertainties, and implications for astrophysical neutrino detection, with recent IceCube results included.

Contribution

It introduces a simple numerical/analytic method to systematically investigate uncertainties in atmospheric neutrino flux predictions.

Findings

Analysis of muon charge ratio implications for neutrino fluxes

Methods to incorporate cosmic-ray spectrum effects

Application to recent IceCube neutrino data

Abstract

This review of atmospheric muons and neutrinos emphasizes the high energy range relevant for backgrounds to high-energy neutrinos of astrophysical origin. After a brief historical introduction, the main distinguishing features of atmospheric $\nu_\mu$ and $\nu_e$ are discussed, along with the implications of the muon charge ratio for the $\nu_\mu/\bar{\nu}_\mu$ ratio. Methods to account for effects of the knee in the primary cosmic-ray spectrum and the energy-dependence of hadronic interactions on the neutrino fluxes are discussed and illustrated in the context of recent results from IceCube. A simple numerical/analytic method is proposed for systematic investigation of uncertainties in neutrino fluxes arising from uncertainties in the primary cosmic-ray spectrum/composition and hadronic interactions.