  We consider the search for gamma-rays produced by the annihilation or decay
of low-mass dark matter which couples to quarks. In this scenario, most of the
photons are produced from the decays of $\pi^0$ or $\eta$ mesons. These decays
produce distinctly different photon signatures due to the difference in meson
mass. We assess the ability of the future MeV-range observatories to constrain
the hadronic final states produced by dark matter annihilation or decay from
the shape of the resulting photon spectrum. We then comment on how this
information can be used to determine properties of the dark matter coupling to
the quark current, based on the approximate symmetries of low-energy QCD.

High Energy Physics - Phenomenology;Cosmology and Nongalactic Astrophysics;High Energy Astrophysical Phenomena