Neutrino interactions with ultralight axion-like dark matter

TL;DR

This paper investigates how ultralight axion-like particles as dark matter could influence high-energy neutrino propagation and flavor composition observed on Earth, providing new insights into neutrino-dark matter interactions.

Contribution

It introduces a detailed model of neutrino interactions with ultralight axion-like particles and predicts their impact on neutrino flavor ratios at Earth, considering different neutrino mass orderings.

Findings

Interactions can alter flavor ratios for certain coupling strengths.

Flavor composition shifts toward electron or muon dominance at high energies.

Current data do not confirm such interactions but suggest further investigation.

Abstract

In this work, we study the propagation of high energy neutrinos produced in extragalactic sources including the effect of a possible interaction with ultralight axion-like particles (UALP) with a mass $m_a\sim 10^{-22} {\rm eV}$ as the constituents of dark matter (DM) under the assumption that their coupling to neutrinos is dominant. We compute the cross section and describe the propagation of a diffuse neutrino flux using transport equations for each mass eigenstate. This allows us to obtain the neutrino fluxes of the different flavors to be observed at the Earth with neutrino telescopes under different assumptions for the flavor composition emitted at the sources and for a normal ordering (NO) or an inverted ordering (IO) of the neutrino masses. If the coupling of neutrinos with UALPs is the same for all flavors ($g_{\nu a}$), we find that interactions change the flavor composition of neutrinos arriving on Earth for $g_{\nu a}\gtrsim 0.5\,{\rm GeV}^{-1}$, causing the electron(muon) flavor to dominate in the NO(IO) case for neutrino energies above $\sim 10^5\,{\rm GeV}$. Although current data on the flavor ratios suggest that interactions with UALP DM do not take place within the range of coupling studied (particularly in the NO case) more data is needed to improve the precision of the experimentally measured flavor composition.