Ratio of hadronic decay rates of J/ψ and ψ(2S) and the ρπ puzzle -: art. no. 114019

The so-called rho pi puzzle of J/psi, and psi (2S) decays is examined using the experimental data available to date. Two different approaches were taken to estimate the ratio of J/psi and psi (2S) hadronic decay rates. While one of the estimates could not yield the exact ratio of psi (2S) to J/psi inclusive hadronic decay rates, the other, based on a computation of the inclusive ggg decay rate for psi (2S)(J/psi) by subtracting other decay rates from the total decay rate, differs by two standard deviations from the naive prediction of perturbative QCD, even though its central value is nearly twice as large as what was naively expected. A comparison between this ratio, upon making corrections for specific exclusive two-body decay modes, and the corresponding experimental data confirms the puzzles in J/psi and psi (2S) decays. We find from our analysis that the exclusively reconstructed hadronic decays of the psi (2S) account for only a small fraction of its total decays, and a ratio exceeding the above estimate should be expected to occur for a considerable number of the remaining decay channels. We also show that the recent new results from the BES experiment provide crucial tests of various theoretical models proposed to explain the puzzle.