The p-anti p decays of P-wave quarkonium and the helicity characteristics of massless QCD

We consider the exclusive p-anti p decays of the quarkonium P-states. Due to the helicity conservation of massless QCD the p-anti p mode is forbidden in this limit for the 1P1 and the 3P0 states. The angular distributions for the decays of the remaining states in the cascade 3S'sub(perpendicular to)->γ3Psub(J)->γ panti p are specific to QCD and can serve as a test of the theory. The same is true of the formation process panti p->3Psub(J)->3Ssub(perpendicular to)γ. In lowest order QCD we obtain overall branching ratios for charmonium of the order of 10-4. (orig.)