Observation of double production in e+e− annihilation

The production of prompt charmonia from the e + e − → q q continuum is studied with the Belle detector at the KEKB asymmetric energy collider. The J/Ψ and Ψ(2S) cross-sections and momentum spectra are measured. The J/Ψ production angle distribution and polarization are determined. The system recoiling against the J/Ψ is studied. We find that a surprisingly high fraction (∼ 60%) of prompt J/Ψ's originates from double c c production.