On the Oscillation of Neutrinos Produced by the Annihilation of Dark Matter inside the Sun

TL;DR

This paper investigates how monochromatic neutrinos from dark matter annihilation inside the Sun oscillate and produce observable annual variations in muon-track events, offering a new way to study dark matter properties.

Contribution

It demonstrates that neutrino oscillation effects from dark matter annihilation produce detectable annual variations, even after spectrum smearing, enabling initial flavor composition analysis.

Findings

Oscillatory terms in neutrino oscillation probability do not average out for monochromatic neutrinos.

Annual variation in muon-track events can reveal initial neutrino flavor composition.

Spectrum smearing due to dark matter thermal distribution is negligible for these effects.

Abstract

The annihilation of dark matter particles captured by the Sun can lead to a neutrino flux observable in neutrino detectors. Considering the fact that these dark matter particles are non-relativistic, if a pair of dark matter annihilates to a neutrino pair, the spectrum of neutrinos will be monochromatic. We show that in this case, even after averaging over production point inside the Sun, the oscillatory terms of the oscillation probability do not average to zero. This leads to interesting observable features in the annual variation of the number of muon track events. We show that smearing of the spectrum due to thermal distribution of dark matter inside the Sun is too small to wash out this variation. We point out the possibility of studying the initial flavor composition of neutrinos produced by the annihilation of dark matter particles via measuring the annual variation of the number of muon-track events in neutrino telescopes.