Astrophysical bounds on the high-energy evolution of neutrino mixing

TL;DR

High-energy astrophysical neutrinos can test the evolution of neutrino mixing parameters at energies unreachable by traditional experiments, providing new bounds on high-energy neutrino physics.

Contribution

This work introduces a method to constrain neutrino mixing evolution at high energies using astrophysical neutrino flavor data, incorporating Standard Model Effective Field Theory.

Findings

Current IceCube data cannot detect neutrino mixing running.

Forecasts suggest future detectors will set unprecedented bounds.

Astrophysical uncertainties weaken but do not eliminate the constraints.

Abstract

While conventional oscillation experiments measure neutrino mixing parameters with high precision, these measurements are strictly confined to sub-TeV scales. At higher energies, renormalization-group effects can cause these parameters to evolve with the transferred momentum, $Q$. High-energy and ultra-high-energy astrophysical neutrinos, spanning TeV to EeV energies, probe high values of $Q$ unreachable by conventional experiments, offering an unprecedented test of high-energy mixing. We use the flavor composition of these neutrinos -- the relative proportions of $\nu_e$, $\nu_\mu$, and $\nu_\tau$ -- to constrain this evolution, both phenomenologically and within dimension-6 Standard Model Effective Field Theory. We account for astrophysical uncertainties -- an unavoidable requirement to obtain realistic results, even though this weakens the bounds. Although present IceCube measurements lack the sensitivity to detect this running, we forecast that upcoming multi-detector combinations will place unprecedented bounds on the high-energy evolution of neutrino mixing.