Electromagnetic neutrino properties: new constraints and new effects

TL;DR

This paper reviews current constraints on neutrino electromagnetic properties, discusses recent experimental hints of nonzero magnetic moments, and explores future prospects for tighter bounds through terrestrial and astrophysical observations.

Contribution

It provides a concise overview of the latest experimental and astrophysical constraints on neutrino electromagnetic properties and discusses potential future improvements.

Findings

XENON1T results suggest possible neutrino magnetic moments near current limits.

Current terrestrial and astrophysical data impose stringent bounds on neutrino charge radii and millicharges.

Future experiments could significantly tighten constraints on neutrino electromagnetic properties.

Abstract

The electromagnetic properties of neutrinos have attracted considerable attention from researchers for many decades (see [1] for a review). However, until recently, there was no indication in favour of nonzero electromagnetic properties of neutrinos either from laboratory experiments with ground-based neutrino sources or from observations of astrophysical neutrino fluxes. The situation changed after the XENON collaboration reported [2] results of the search for new physics with low-energy electronic recoil data recorded with the XENON1T detector. The results show an excess of events over the known backgrounds in the recoil energy which, as one of the possible explanations, admit the presence of a sizable neutrino magnetic moment, the value of which is of the order of the existing laboratory limitations. In these short notes we give a brief introduction to neutrino electromagnetic properties and focus on the most important constraints on neutrino magnetic moments, charge radii and millicharges from the terrestrial experiments and astrophysical considerations. The promising new possibilities for constraining neutrino electromagnetic properties in future experiments are also discussed.