Observation of J/psi-->3gamma

Phys Rev Lett. 2008 Sep 5;101(10):101801. doi: 10.1103/PhysRevLett.101.101801. Epub 2008 Sep 2.

Abstract

We report the first observation of the decay J/psi-->3gamma. The signal has a statistical significance of 6sigma and corresponds to a branching fraction of B(J/psi-->3gamma)=(1.2+/-0.3+/-0.2)x10;{-5}, in which the errors are statistical and systematic, respectively. The measurement uses psi(2S)-->pi;{+}pi;{-}J/psi events acquired with the CLEO-c detector operating at the CESR e;{+}e;{-} collider.