Neutrino Self-Interactions: A White Paper

TL;DR

This white paper reviews the current understanding, theoretical motivations, and experimental prospects for neutrino self-interactions, emphasizing their potential to reveal physics beyond the Standard Model across various energy scales.

Contribution

It provides a comprehensive overview of neutrino self-interactions, integrating cosmological, astrophysical, and laboratory probes, and discusses future experimental capabilities for discovery.

Findings

Current experiments have limited sensitivity to neutrino self-interactions.

Theoretical models suggest connections to neutrino masses and dark matter.

Next-generation searches could potentially detect beyond-the-Standard-Model interactions.

Abstract

Neutrinos are the Standard Model (SM) particles which we understand the least, often due to how weakly they interact with the other SM particles. Beyond this, very little is known about interactions among the neutrinos, i.e., their self-interactions. The SM predicts neutrino self-interactions at a level beyond any current experimental capabilities, leaving open the possibility for beyond-the-SM interactions across many energy scales. In this white paper, we review the current knowledge of neutrino self-interactions from a vast array of probes, from cosmology, to astrophysics, to the laboratory. We also discuss theoretical motivations for such self-interactions, including neutrino masses and possible connections to dark matter. Looking forward, we discuss the capabilities of searches in the next generation and beyond, highlighting the possibility of future discovery of this beyond-the-SM physics.