The decay of J/ψ to three photons is studied using ψ(3686) →π+π-J/ψ in a sample of 1.0641×108 ψ(3686) events collected with the BESIII detector. Evidence of the direct decay of ηc to two photons, ηc→γγ , is reported, and the product branching fraction is determined to be B(J/ψ→γηc,ηc→γγ)= (4.5±1.2±0.6)×10-6, where the first error is statistical and the second is systematic. The branching fraction for J/ψ→3γ is measured to be (11.3±1.8±2.0) ×10-6 with improved precision.
|Original language||English (US)|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Feb 8 2013|