Neutrino charge constraints from scattering to the weak gravity conjecture to neutron stars

TL;DR

This paper reviews theoretical models allowing neutrinos to have tiny electric charges, derives new bounds on these charges from observational data and fundamental physics principles, and discusses implications for particle physics and astrophysics.

Contribution

It introduces new upper bounds on neutrino charges from astrophysical observations and the weak gravity conjecture, expanding constraints beyond previous limits.

Findings

New upper bounds on muon and tau neutrino charges from astrophysics.

A flavor-universal lower bound on neutrino charges from the weak gravity conjecture.

Stringent direct bounds on neutrino charges based on observational data.

Abstract

In various extensions of the Standard Model of particle physics, and intriguingly even in the three-generation Standard Model without neutrino masses, neutrinos are allowed to have very tiny electric charges. After a review of the theoretical scenarios that allow the emergence of such charges, we discuss the existing observational limits and we derive new stringent direct upper bounds for the charges of the muon and tau neutrinos. We also point out a flavor-universal lower bound on neutrino charges which is obtained from the weak gravity conjecture, that is based on the hypothesis that gravity is the weakest force. We finally present a new flavor-universal upper bound on neutrino charges based on astrophysical observations of Magnetars.