Sterile neutrinos as a possible explanation for the upward air shower events at ANITA

TL;DR

This paper explores sterile neutrinos as a potential explanation for ANITA's unusual upward air shower events, suggesting they could account for the anomalies but are unlikely to explain both ANITA and IceCube observations simultaneously.

Contribution

It introduces the sterile neutrino hypothesis as an alternative explanation for ANITA's anomalous events, considering quantum decoherence and flux constraints.

Findings

Sterile neutrinos can explain ANITA anomalies under certain conditions.

IceCube should observe more events if sterile neutrinos are the cause.

Sterile neutrino explanation is unlikely to account for both ANITA and IceCube events simultaneously.

Abstract

The ANITA experiment has observed two unusual upgoing air shower events which are consistent with the $\tau$-lepton decay origin. However, these events are in contradiction with the standard neutrino-matter interaction models as well as the $\rm EeV$ diffuse neutrino flux limits set by the IceCube and the cosmic ray facilities like AUGER. In this paper, we have reinvestigated the possibility of using sterile neutrino hypothesis to explain the ANITA anomalous events. The diffuse flux of the sterile neutrinos is less constrained by the IceCube and AUGER experiments due to the small active-sterile mixing suppression. The quantum decoherence effect should be included for describing the neutrino flux propagating in the Earth matter, because the interactions between neutrinos and the Earth matter are very strong at the EeV scale. After several experimental approximations, we show that the ANITA anomaly itself is able to be explained by the sterile neutrino origin, but we also predict that the IceCube observatory should have more events than ANITA. It makes the sterile neutrino origin very unlikely to account for both of them simultaneously. A more solid conclusion can be drawn by the dedicated ANITA signal simulations.