Search for exotic contributions to atmospheric neutrino oscillations

TL;DR

This study analyzes atmospheric neutrino data to search for exotic effects like Lorentz invariance violation, setting stringent limits that support standard neutrino oscillation models and constrain new physics.

Contribution

It provides the first significant limits on Lorentz invariance violation parameters using atmospheric neutrino data, reinforcing the dominance of standard oscillation effects.

Findings

Stringent 90% C.L. limits on Lorentz violation parameters

Data disfavor exotic effects at sub-dominant levels

Results support standard mass-induced neutrino oscillations

Abstract

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant effect. The data disfavor these possibilities even at a sub-dominant level; stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter $|\Delta v| < 6 \times 10^{-24}$ at $\sin 2{\theta}_v$ = 0 and $|\Delta v| < 2.5 \div 5 \times 10^{-26}$ at $\sin 2{\theta}_v$ = $\pm$1. The limits can be re-interpreted as bounds on the Equivalence Principle violation parameters.