Probing Secret Interactions of Astrophysical Neutrinos in the High-Statistics Era

TL;DR

This paper explores how future high-energy neutrino observations can test potential secret neutrino self-interactions, using a comprehensive theoretical framework and a new analysis code, to probe physics beyond the Standard Model.

Contribution

It provides a detailed, realistic methodology for testing secret neutrino interactions with IceCube-Gen2, including a new code for broader studies.

Findings

IceCube-Gen2 can detect cosmologically relevant neutrino self-interactions.

A comprehensive treatment of neutrino physics enhances sensitivity to new interactions.

The release of nuSIProp facilitates future research on neutrino self-interactions.

Abstract

Do neutrinos have sizable self-interactions? They might. Laboratory constraints are weak, so strong effects are possible in astrophysical environments and the early universe. Observations with neutrino telescopes can provide an independent probe of neutrino self ("secret") interactions, as the sources are distant and the cosmic neutrino background intervenes. We define a roadmap for making decisive progress on testing secret neutrino interactions governed by a light mediator. This progress will be enabled by IceCube-Gen2 observations of high-energy astrophysical neutrinos. Critical to this is our comprehensive treatment of the theory, taking into account previously neglected or overly approximated effects, as well as including realistic detection physics. We show that IceCube-Gen2 can realize the full potential of neutrino astronomy for testing neutrino self-interactions, being sensitive to cosmologically relevant interaction models. To facilitate forthcoming studies, we release nuSIProp, a code that can also be used to study neutrino self-interactions from a variety of sources.