Comprehensive approach to tau-lepton production by high-energy tau neutrinos propagating through the Earth

Abstract

There has been a recent surge in interest in the detection of τ lepton-induced air showers from detectors at altitude. When a τ neutrino (ντ ) enters the Earth it produces τ leptons as a result of nuclear charged current interactions. In some cases, this process results in a τ lepton exiting the surface of the Earth, which can subsequently decay in the atmosphere and produce an extensive air shower. These upward-going air showers can be detected via fluorescence, optical Cherenkov, or geomagnetic radio emission. Several experiments have been proposed to detect these signals. We present a comprehensive simulation of the production of τ leptons by ντ 's propagating through Earth to aid the design of future experiments. These simulations for ντ 's and leptons in the energy range from 10 15 eV to 10 21 eV treat the full range of incidence angles from Earth-skimming to diametrically-traversing. Propagation of ντ 's and leptons include the effects of rock and an ocean or ice layer of various thicknesses. The interaction models include ντ regeneration and account for uncertainties in the Standard Model neutrino cross-section and in the photo-nuclear contribution to the τ energy loss rate.

Can the ANITA anomalous events be due to new physics?

“…With these analytic formulae, we can reproduce the conversion probability given by the Monte Carlo simulations in ref. [18] with vanishing ice thickness for θ em 3 • . Unlike the simulations, we neglect τ regeneration [19], which is important for larger θ em and lowĒ τ .…”

Observing EeV neutrinos through Earth: GZK and the anomalous ANITA events

“…[19]. However, in this work we consider neutrino propagation at EeV energies and higher, where this approximation no longer holds and careful treatment of tau energy losses is required; see [40,51] for recent implementations and discussions.…”

Anomalous ANITA air shower events and tau decays

“…A feature unique to tau neutrinos is the significance of tau neutrino regeneration with neutrino interactions in the Earth [42,[55][56][57][58][59][60]. Tau neutrino regeneration comes from tau neutrino charged-current production of taus which subsequently decay back to ν τ .…”