Probing Neutrino Flavor Transition Mechanism with Ultra High Energy Astrophysical Neutrinos

TL;DR

This paper introduces a new parameter to directly probe neutrino flavor transition mechanisms using ultra-high energy astrophysical neutrinos, independent of mu-tau symmetry assumptions, and tests it with various models.

Contribution

The paper presents a model-independent parametrization and a new observable R to analyze neutrino flavor transitions without assuming mu-tau symmetry.

Findings

The parameter R effectively probes flavor transitions.

The new observable constrains flavor transition models.

Model testing demonstrates the utility of R in neutrino physics.

Abstract

Observation of ultra-high energy astrophysical neutrinos and identification of their flavors have been proposed for future neutrino telescopes. The flavor ratio of astrophysical neutrinos observed on the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during propagations of these neutrinos. The flavor transition mechanisms are well-classified with our model-independent parametrization. We find a new parameter R={\phi}_e/({\phi}_{\mu} + {\phi}_{\tau}) can probe directly the flavor transition in the framework of our model-independent parametrization, without the assumption of the {\nu}_{\mu}-{\nu}_{\tau} symmetry. A few flavor transition models are employed to test our parametrization with this new observable. The observational constraints on flavor transition mechanisms by the new observable is discussed through our model-independent parametrization.