Indirect Detection of Low-mass Dark Matter Through the $\pi^0$ and $\eta$ Windows

TL;DR

This paper explores how future MeV gamma-ray observatories can detect low-mass dark matter by analyzing photon spectra from meson decays, helping to understand dark matter-quark interactions.

Contribution

It introduces a method to distinguish dark matter annihilation or decay signatures via meson decay photon spectra in the MeV range, linking spectral features to dark matter coupling properties.

Findings

Photon spectra from $$ and $$ meson decays have distinct signatures.

Future MeV observatories can constrain dark matter hadronic final states.

Spectral analysis can infer properties of dark matter-quark couplings.

Abstract

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.