Do neutrinos bend? Consequences of an ultralight gauge field as dark matter

TL;DR

This paper explores how an ultralight gauge boson as dark matter could influence neutrino propagation, potentially causing delays detectable by future supernova neutrino observations, and discusses current and future experimental bounds.

Contribution

It introduces the idea that ultralight gauge bosons coupled to neutrinos can affect neutrino signals from supernovae, providing a new way to test dark matter models.

Findings

Neutrino delays of 10^{-8} to 10^1 seconds are possible due to gauge boson effects.

Future experiments like DUNE can probe gauge couplings down to 10^{-27}.

The model offers a novel observational signature for ultralight dark matter.

Abstract

An ultralight gauge boson could address the missing cosmic dark matter, with its transverse modes contributing to a relevant component of the galactic halo today. We show that, in the presence of a coupling between the gauge boson and neutrinos, these transverse modes affect the propagation of neutrinos in the galactic core. Neutrinos emitted from galactic or extra-galactic supernovae could be delayed by $\delta t = \left(10^{-8}-10^1\right)\,$s for the gauge boson masses $m_{A'} = \left(10^{-23}-10^{-19}\right)\,$eV and the coupling with the neutrino $g= 10^{-27}-10^{-20}$. While we do not focus on a specific formation mechanism for the gauge boson as the dark matter in the early Universe, we comment on some possible realizations. We discuss model-dependent current bounds on the gauge coupling from fifth-force experiments, as well as future explorations involving supernovae neutrinos. We consider the concrete case of the DUNE facility, where the coupling can be tested down to $g \simeq 10^{-27}$ for neutrinos coming from a supernova event at a distance $d = 10\,$kpc from Earth.