  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.
