Observation of the radiative decays of to

Katrenko, P.*; Tanida, Kiyoshi   ; Belle Collaboration*; 168 of others*

We report the first observation of the radiative decay of the into a charmonium state. The statistical significance of the observed signal of is 6.3 standard deviations including systematics. The branching fraction is calculated to be Br() = . We also searched for radiative decays into and and set upper limits on their branching fractions. These results are obtained from a 24.9 fb data sample collected with the Belle detector at the KEKB asymmetric-energy collider at a center-of-mass energy equal to the mass using tagging by the transitions.