How Unequal Fluxes of High Energy Astrophysical Neutrinos and Antineutrinos can Fake New Physics

TL;DR

This paper explores how unequal fluxes of astrophysical neutrinos and antineutrinos can mimic signals of new physics, emphasizing the importance of considering potential discrepancies in flavor ratios for accurate interpretation of IceCube data.

Contribution

It highlights the potential for flavor ratio differences between neutrinos and antineutrinos to lead to misinterpretations of astrophysical neutrino data, urging more nuanced analysis.

Findings

Differences in neutrino and antineutrino flavor ratios can mimic new physics signals.

Assuming equal flavor ratios may lead to incorrect conclusions about neutrino sources.

Future analyses should account for possible flux discrepancies to avoid misleading results.

Abstract

Flavor ratios of very high energy astrophysical neutrinos, which can be studied at the Earth by a neutrino telescope such as IceCube, can serve to diagnose their production mechanism at the astrophysical source. The flavor ratios for neutrinos and antineutrinos can be quite different as we do not know how they are produced in the astrophysical environment. Due to this uncertainty the neutrino and antineutrino flavor ratios at the Earth also could be quite different. Nonetheless, it is generally assumed that flavor ratios for neutrinos and antineutrinos are the same at the Earth, in fitting the high energy astrophysical neutrino data. This is a reasonable assumption for the limited statistics for the data we currently have. However, in the future the fit must be performed allowing for a possible discrepancy in these two fractions in order to be able to disentangle different production mechanisms at the source from new physics in the neutrino sector. To reinforce this issue, in this work we show that a wrong assumption about the distribution of neutrino flavor ratios at the Earth may indeed lead to misleading interpretations of IceCube results.