Constraints on Light Dark Matter from Single-Photon Decays of Heavy
  Quarkonium
  We investigate constraints on the interactions of light dark matter with
Standard Model quarks in a framework with effective contact operators mediating
the decay of heavy flavor bound state quarkonium to dark matter and a photon.
When considered in combination with decays to purely invisible final states,
constraints from heavy quarkonium decays at high intensity electron-positron
colliders can complement missing energy searches at high energy colliders and
provide sensitivity to dark matter masses difficult to probe at direct and
indirect detection experiments. We calculate the approximate limits on the
branching fraction for $\Upsilon (1 S)$ decays to dark matter and a photon.
Given the approximate limits on the branching fractions for all dimension 6 or
lower contact operators, we present the corresponding limits on the interaction
strength for each operator and the inferred limits on dark matter-nucleon
scattering. Complementary constraints on dark matter annihilation from
gamma-ray searches from dwarf spheroidal galaxies are also considered.
