Testing decay of astrophysical neutrinos with incomplete information

TL;DR

This paper proposes a method to use IceCube astrophysical neutrino data to significantly improve constraints on neutrino decay lifetimes, overcoming current uncertainties and potentially ruling out decay effects in other experiments.

Contribution

It introduces a novel approach to analyze astrophysical neutrino data for decay constraints, accounting for uncertainties and providing a practical roadmap for future analyses.

Findings

Sensitivity to neutrino decay lifetime can reach ~10 seconds (m/eV)

Method can rule out decay effects in solar, atmospheric, terrestrial neutrino experiments

Provides a framework for managing uncertainties in astrophysical neutrino analysis

Abstract

Neutrinos mix and have mass differences, so decays from one to another must occur. But how fast? The best direct limits on non-radiative decays, based on solar and atmospheric neutrinos, are weak, $\tau \gtrsim 10^{-3}$ s ($m$/eV) or much worse. Greatly improved sensitivity, $\tau \sim 10^3$ s ($m$/eV), will eventually be obtained using neutrinos from distant astrophysical sources, but large uncertainties --- in neutrino properties, source properties, and detection aspects --- do not allow this yet. However, there is a way forward now. We show that IceCube diffuse neutrino measurements, supplemented by improvements expected in the near term, can increase sensitivity to $\tau \sim 10$ s ($m$/eV) for all neutrino mass eigenstates. We provide a roadmap for the necessary analyses and show how to manage the many uncertainties. If limits are set, this would definitively rule out the long-considered possibility that neutrino decay affects solar, atmospheric, or terrestrial neutrino experiments.