We search for the rare radiative decay D 0 → γγ using a data sample with an integrated luminosity of 832 fb−1 recorded by the Belle detector at the KEKB e +e − asymmetric-energy collider. We find no statistically significant signal and set an upper limit on the branching fraction of B(D 0 → γγ) < 8.5 × 10−7 at 90% confidence level. This is the most restrictive limit on the decay channel to date.
Physical Review D
Digital Object Identifier (DOI)