Closed-flavor pi + J/psi and pi + Upsilon Cross Sections at Low Energies from Dipion Decays

The scale of low energy c-cbar and b-bbar cross sections on light hadrons is of great importance to searches for the quark gluon plasma using the heavy-quarkonium suppression signature. Unfortunately, little is known about these near-threshold cross sections at present, and recent theoretical estimates span many orders of magnitude. Here we use experimental data on the four observed closed-flavor heavy quarkonium hadronic decays psi' -> pi pi J/psi, Upsilon' -> pi pi Upsilon, Upsilon'' -> pi pi Upsilon and Upsilon'' -> pi pi Upsilon', combined with simple models of the transition amplitudes, to estimate the pion scattering cross sections of c-cbar and b-bbar mesons near threshold. Specifically we consider the closed-flavor reactions pi J/psi -> pi psi', pi Upsilon -> pi Upsilon', pi Upsilon -> pi Upsilon'' and pi Upsilon' -> pi Upsilon'' and their time-reversed analogues. Our results may be useful in constraining theoretical models of the strong interactions of heavy quarkonia, and can be systematically improved through future detailed studies of dipion decays, notably psi' -> pi pi J/psi and Upsilon'' -> pi pi Upsilon.Comment: 6 pages, 6 figure

Evidence for kappa Meson Production in J/psi -> bar{K}^*(892)^0K^+pi^- Process

Based on 58 million BESII J/psi events, the bar{K}^*(892)^0K^+pi^- channel in K^+K^-pi^+pi^- is studied. A clear low mass enhancement in the invariant mass spectrum of K^+pi^- is observed. The low mass enhancement does not come from background of other J/psi decay channels, nor from phase space. Two independent partial wave analyses have been performed. Both analyses favor that the low mass enhancement is the kappa, an isospinor scalar resonant state. The average mass and width of the kappa in the two analyses are 878 +- 23^{+64}_{-55} MeV/c^2 and 499 +- 52^{+55}_{-87} MeV/c^2, respectively, corresponding to a pole at (841 +- 30^{+81}_{-73}) - i(309 +- 45^{+48}_{-72}) MeV/c^2.Comment: 17 pages, 5 figure

Observation of charged kappa in J/psi -> K*(892)-+Kspi+-, K*(892)-+ -> Kspi-+ at BESII

Using 58 million J/psi decays obtained by BESII, a charged kappa particle is observed in the analysis of the Kspi+- system recoiling against K*(892)-+ selected in J/psi -> KsKspi+pi-. The mass and width values of the charged kappa are obtained to be (826+-49_{-34}^{+49}) MeV/c^2 and (449+-156_{-81}^{+144}) MeV/c^2 for the Breit-Wigner parameters, and the pole position is determined to be (764+-63_{-54}^{+71})-i(306+-149_{-85}^{+143}) MeV/c^2. They are in good agreement with those of the neutral kappa observed by the BES collaboration.Comment: 15 pages, 9 figure