Why Tau First?

TL;DR

This paper argues that tau neutrinos are the most promising for early detection in high-energy neutrino astronomy due to their unique properties and recent favorable scientific coincidences, potentially observable by Auger.

Contribution

It highlights the reasons why tau neutrinos should be the first detected in high-energy neutrino astronomy, emphasizing recent scientific developments and observational strategies.

Findings

Tau neutrinos are produced by UHECR interactions and muon mixing.

Horizontal tau air-showers can be detected by current observatories.

Detection of tau neutrinos could be imminent within this decade.

Abstract

Electron neutrino has been the first neutral lepton to be foreseen and discovered last century. The un-ordered muon and its neutrino arose later by cosmic rays. The tau discover, the heaviest, the most unstable charged lepton, was found surprisingly on 1975. Its neutrino was hardly revealed just on 2000. So why High Energy Neutrino Astronomy should rise first via tau neutrino, the last, the most rare one? The reasons are based on a chain of three favorable coincidences found last decade: the neutrino masses and their flavor mixing, the UHECR opacity on Cosmic Black Body (GZK cut off on BBR), the amplified tau air-shower decaying in flight. Indeed guaranteed UHE GZK tau neutrinos, feed by muon mixing, while skimming the Earth might lead to boosted UHE tau, mostly horizontal ones. These UHE lepton decay in flight are spread, amplified, noise free Air-Shower: a huge event for an unique particle. To be observed soon: within Auger sky, in present decade. Its discover may sign of the first tau appearance.