Exclusive QCD predictions for proton-antiproton decay rates of ³D₁-states charmonium states

Using familiar methods of exclusive QCD, we derive the amplitude for the coupling of J=1 quarkonium D-states to proton-antiproton pairs. Including the ³D₁ contribution, we then evaluate the Ψ′ →pp decay width and find that the |2 ³S₁〉-|1 ³D₁〉 mixing angle solution φ=-(28±2)° is favored by the observed Ψ′ decay rate. Using this solution, we then find that Γ(Ψ″→p p)/Γ(Ψ→pp) is in the range 0.07-0.31 depending on the assumed nucleon wavefunction.