A recent suggestion that the observations of monochromatic photons from annihilation of photinos into quarkonium plus a photon could be a signature of dark-matter photinos is extended to include all S- and P-wave bound quarkonium states for a general interaction Lagrangian and an estimate of the cross sections is given. We also propose the process λλ¯→γγ as a potentially rich source of monochromatic photons and estimate its strength.

• Received 3 November 1987

DOI:https://doi.org/10.1103/PhysRevD.37.3737