Violations of Lorentz invariance in the neutrino sector: an improved analysis of anomalous threshold constraints

TL;DR

This paper investigates how violations of Lorentz invariance in the neutrino sector affect reaction thresholds and neutrino spectra, providing refined constraints from atmospheric and cosmogenic neutrino observations.

Contribution

It introduces a simplified rotationally invariant model to analyze finite baseline and energy dispersion effects on anomalous reactions, improving threshold constraint methods.

Findings

Anomalous reactions may not sharply cut off neutrino spectra as previously assumed.

Revised analysis enhances constraints from atmospheric high-energy neutrinos.

Implications for detecting Lorentz invariance violations in neutrino experiments.

Abstract

Recently there has been a renewed activity in the physics of violations of Lorentz invariance in the neutrino sector. Flavor dependent Lorentz violation, which generically changes the pattern of neutrino oscillations, is extremely tightly constrained by oscillation experiments. Flavor independent Lorentz violation, which does not introduce new oscillation phenomena, is much more weakly constrained with constraints coming from time of flight and anomalous threshold analyses. We use a simplified rotationally invariant model to investigate the effects of finite baselines and energy dependent dispersion on anomalous reaction rates in long baseline experiments and show numerically that anomalous reactions do not necessarily cut off the spectrum quite as sharply as currently assumed. We also present a revised analysis of how anomalous reactions can be used to cast constraints from the observed atmospheric high energy neutrinos and the expected cosmogenic ones.