Sterile Neutrinos and Flavor Ratios in IceCube

TL;DR

This paper explores how light sterile neutrinos could influence the flavor ratios of astrophysical neutrinos detected by IceCube, providing constraints on sterile neutrino parameters and implications for dark matter decay signatures.

Contribution

It introduces a comprehensive analysis of sterile neutrino effects on astrophysical neutrino flavor ratios and constrains sterile neutrino parameters using IceCube data.

Findings

Sterile neutrinos can alter flavor ratios observed in IceCube.

Constraints on sterile neutrino mixing parameters from global data.

Exclusion limits on dark matter properties based on neutrino flavor analysis.

Abstract

The flavor composition of astrophysical neutrinos observed in neutrino telescopes is a powerful discriminator between different astrophysical neutrino production mechanisms and can also teach us about the particle physics properties of neutrinos. In this paper, we investigate how the possible existence of light sterile neutrinos can affect these flavor ratios. We consider two scenarios: (i) neutrino production in conventional astrophysical sources, followed by partial oscillation into sterile states; (ii) neutrinos from dark matter decay with a primary flavor composition enhanced in tau neutrinos or sterile neutrinos. Throughout the paper, we constrain the sterile neutrino mixing parameters from a full global fit to short and long baseline data. We present our results in the form of flavor triangles and, for scenario (ii), as exclusion limits on the dark matter mass and lifetime, derived from a fit to IceCube high energy starting events and through-going muons. We argue that identifying a possible flux of neutrinos from dark matter decay may require analyzing the flavor composition as a function of neutrino energy.