# Anomalous ANITA air shower events and tau decays

## TL;DR

This paper investigates anomalous ANITA air shower events, evaluating detection models and sterile neutrino scenarios, concluding standard and sterile neutrinos are unlikely sources for these unusual upward-going air showers.

## Contribution

The study provides a simplified detection model for ANITA, analyzes sterile neutrino contributions, and assesses dark matter decay scenarios related to the anomalous events.

## Key findings

- Standard model tau neutrinos cannot explain the events.
- Sterile neutrinos with suppressed interactions are unlikely sources.
- Dark matter decay scenarios do not account for the observed events.

## Abstract

Two unusual neutrino events in the Antarctic Impulse Transient Antenna (ANITA) appear to have been generated by air showers from a particle emerging from the Earth at angles 25-35 degrees above the horizon. We evaluate the effective aperture for ANITA with a simplified detection model to illustrate the features of the angular dependence of expected events for incident standard model tau neutrinos and for sterile neutrinos that mix with tau neutrinos. We apply our sterile neutrino aperture results to a dark matter scenario with long-lived supermassive dark matter that decay to sterile neutrino-like particles. We find that for up-going air showers from tau decays, from isotropic fluxes of standard model, sterile neutrinos or other particles that couple to the tau through suppressed weak interaction cross sections cannot be responsible for the unusual events.