Secondary atmospheric tau neutrino production

TL;DR

This paper calculates the flux of tau neutrinos produced by muons in the atmosphere, comparing different sources and showing the dominance of prompt tau neutrinos at energies above a few TeV.

Contribution

It provides a numerical analysis of tau neutrino fluxes from muon decay, including cascade equations and flux comparisons for various angles and energies.

Findings

Prompt atmospheric tau neutrinos dominate at energies above a few TeV.

The flux of tau neutrinos varies with zenith angle and energy.

Numerical results for tau production Z moments are provided.

Abstract

We evaluate the flux of tau neutrinos produced from the decay of pair produced taus from incident muons using a cascade equation analysis. To solve the cascade equations, our numerical result for the tau production $Z$ moment is given. Our results for the flux of tau neutrinos produced from incident muons are compared to the flux of tau neutrinos produced via oscillations and the direct prompt atmospheric tau neutrino flux. Results are given for both downward and upward going neutrinos fluxes and higher zenith angles are discussed. We conclude that the direct prompt atmospheric tau neutrino flux dominates these other atmospheric sources of tau neutrinos for neutrino energies larger than a few TeV for upward fluxes, and over a wider range of energy for downward fluxes.