New Physics in Astrophysical Neutrino Flavor

TL;DR

This paper investigates how new physics operators could alter the flavor composition of ultra high energy astrophysical neutrinos, showing that precise measurements could significantly improve constraints on such new physics.

Contribution

It introduces the first comprehensive study of new physics effects on astrophysical neutrino flavor content using effective operators, highlighting maximal possible effects within current limits.

Findings

New physics can cause maximal flavor content effects within current operator limits.

Precise flavor measurements at Earth can vastly improve bounds on new physics.

Current IceCube data fits are compatible with various new physics scenarios.

Abstract

Astrophysical neutrinos are powerful tools to investigate the fundamental properties of particle physics through their flavor content. In this paper, we perform the first general new physics study on ultra high energy neutrino flavor content by introducing effective operators. We find that at the current limits on these operators, new physics terms cause maximal effects on the flavor content, however, the flavor content at Earth is confined to a region related to the assumed initial flavor content. Furthermore, we conclude that a precise measure of the flavor content at Earth will provide orders of magnitude improvement on new physics bounds. Finally, we discuss the current best fits of flavor content of the IceCube data and their interplay with new physics scenarios.