Which is the flavor of cosmic neutrinos seen by IceCube?

TL;DR

This paper analyzes IceCube's high-energy neutrino data to determine the flavor composition of cosmic neutrinos, incorporating passing muons to support the detection and flavor hypothesis.

Contribution

It introduces the first analysis including passing muons and compares flavor predictions from different production mechanisms considering oscillation uncertainties.

Findings

Cosmic neutrinos are detected with flavor ratios consistent with expectations.

Passing muons support the presence of cosmic neutrinos.

Different production mechanisms yield distinguishable flavor predictions.

Abstract

We analyze the high-energy neutrino events observed by IceCube, aiming to probe the initial flavor of cosmic neutrinos. We study the track-to-shower ratio of the subset with energy above 60 TeV, where the signal is expected to dominate and show that different production mechanisms give rise to different predictions even accounting for the uncertainties due to neutrino oscillations. We include for the first time the passing muons observed by IceCube in the analysis. They corroborate the hypotheses that cosmic neutrinos have been seen and their flavor matches expectations.