Measurement of the Three-Flavor Composition of Astrophysical Neutrinos with Contained IceCube Events

TL;DR

This study analyzes 11.4 years of IceCube data to measure the flavor composition of astrophysical neutrinos, providing insights into their sources and the physics of neutrino oscillations.

Contribution

First measurement of the three-flavor composition of astrophysical neutrinos using contained IceCube events over 11.4 years.

Findings

Constraints on the neutrino flavor ratio at Earth

Implications for neutrino production mechanisms in astrophysical sources

Enhanced understanding of neutrino oscillation effects during propagation

Abstract

The IceCube Neutrino Observatory at the South Pole detects neutrinos from the entire sky, both of astrophysical and atmospheric origin, via the Cherenkov light emitted when these neutrinos interact in the ice, giving rise to rapidly moving charged particles. Neutrino events with vertices contained within the detector volume are useful for studying the neutrino flavor ratio, as they allow for a better reconstruction of the event morphology. The Medium Energy Starting Events (MESE) data sample is a selection of such events with energies of at least 1 TeV. This sample includes electron-, muon-, and tau-neutrino events, processed consistently. We use it to constrain the flavor ratio of astrophysical neutrinos at Earth, which in turn informs us of the flavor composition at the source itself. In this talk, we will present the results of this study, based on 11.4 years of IceCube data.