Search for a Lorentz invariance violation in atmospheric neutrino oscillations using MACRO data

TL;DR

This study tests Lorentz invariance in atmospheric neutrino oscillations using MACRO data, finding no evidence of violation and setting strict limits on related parameters, thus supporting standard neutrino oscillation models.

Contribution

It provides the first stringent experimental limits on Lorentz invariance violation effects in atmospheric neutrino oscillations using MACRO data.

Findings

Lorentz invariance violation effects are disfavored at a sub-dominant level.

Stringent 90% confidence level limits are established on violation parameters.

Results also constrain parameters related to the violation of the Equivalence Principle.

Abstract

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of special relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of nu_mu <--> nu_tau transitions. The data disfavour these exotic possibilities even at a sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameters. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the Equivalence Principle.