Testing Lorentz Invariance with Neutrinos from Ultrahigh Energy Cosmic Ray Interactions

TL;DR

This paper investigates how tiny violations of Lorentz invariance could alter the flux and energy spectrum of high-energy neutrinos from ultrahigh energy cosmic ray interactions, offering a way to test LIV through neutrino observations.

Contribution

It calculates the impact of Lorentz invariance violation on high-energy neutrino fluxes and discusses how current and future detectors can test for LIV effects.

Findings

LIV reduces the flux of the highest energy neutrinos.

LIV shifts the peak of the neutrino energy flux spectrum to lower energies.

Neutrino observations can serve as a test for LIV at ultra-high energies.

Abstract

We have previously shown that a very small amount of Lorentz invariance violation (LIV), which suppresses photomeson interactions of ultrahigh energy cosmic rays (UHECRs) with cosmic background radiation (CBR) photons, can produce a spectrum of cosmic rays that is consistent with that currently observed by the Pierre Auger Observatory (PAO) and HiRes experiments. Here, we calculate the corresponding flux of high energy neutrinos generated by the propagation of UHECR protons through the CBR in the presence of LIV. We find that LIV produces a reduction in the flux of the highest energy neutrinos and a reduction in the energy of the peak of the neutrino energy flux spectrum, both depending on the strength of the LIV. Thus, observations of the UHE neutrino spectrum provide a clear test for the existence and amount of LIV at the highest energies. We further discuss the ability of current and future proposed detectors make such observations.