Diffuse Ultra-High Energy Neutrino Fluxes and Physics Beyond the Standard Model

TL;DR

This paper investigates how physics beyond the Standard Model, such as neutrino decay and Lorentz violation, can cause detectable spectral distortions in ultra-high energy neutrino fluxes, offering new ways to probe fundamental physics.

Contribution

It introduces the idea that spectral differences in neutrino fluxes at Earth can reveal new physics beyond the Standard Model during neutrino propagation.

Findings

Spectral distortions indicate physics beyond the Standard Model.

UHE neutrino detectors can constrain neutrino lifetimes and Lorentz violation.

Significant flux distortions can reveal neutrino decay and mass hierarchy.

Abstract

We study spectral distortions of diffuse ultra-high energy (UHE) neutrino flavour fluxes resulting due to physics beyond the Standard Model (SM). Even large spectral differences between flavours at the source are massaged into a common shape at earth by SM oscillations, thus, any significant observed spectral differences are an indicator of new physics present in the oscillation probability during propagation. Neutrino decay and Lorentz symmetry violation (LV) are examples, and result in significant distortion of the fluxes and the well-known bounds on them, which may allow UHE detectors to probe lifetimes, the mass hierarchy and LV parameters over a broad range.