A comprehensive analysis of anomalous ANITA events disfavors a diffuse tau-neutrino flux origin

Understand

Recently, the ANITA collaboration reported on two upward-going extensive air shower events consistent with a primary particle that emerges from the surface of the ice.

• These events may be of $\nu_\tau$ origin, in which the neutrino interacts within the Earth to produce a $\tau$ lepton that emerges from the Earth, decays in the atmosphere, and initiates an extensive air shower.
• In this paper we estimate an upper bound on the ANITA acceptance to a diffuse $\nu_\tau$ flux detected via $\tau$-lepton-induced air showers within the bounds of Standard Model (SM) uncertainties.
• By comparing this estimate with the acceptance of Pierre Auger Observatory and IceCube and assuming SM interactions, we conclude that a $\nu_\tau$ origin of these events would imply a neutrino flux at least two orders of magnitude above current bounds.