We investigate the psi(3770) non-DD decays into VP, where V and P denote vector and pseudoscalar mesons, respectively, via Okubo-Zweig-Iizuka-rule-evading intermediate meson rescatterings in an effective Lagrangian theory. By identifying the leading meson loop transitions and constraining the model parameters with the available experimental data for psi(3770)-->J/psieta, phieta, and rhopi, we succeed in making a quantitative prediction for all psi(3770)-->VP with BRVP from 0.41% to 0.64%. It indicates that the Okubo-Zweig-Iizuka-rule-evading long-range interactions play a role in psi(3770) strong decays, and could be a key towards a full understanding of the mysterious psi(3770) non-DD decay mechanism.

Low-energy scattering of D Ãþ and " D 0 1 meson are studied using quenched lattice QCD with improved lattice actions on anisotropic lattices. The calculation is performed within Lüscher's finite-size formalism, which establishes the relation between the scattering phase in the infinite volume and the exact energy level in the finite volume. The threshold scattering parameters, namely, the scattering length a 0 and the effective range r 0 , for the s-wave scattering in J P ¼ 0 À channel are extracted. After the chiral and continuum extrapolations, we obtain: a 0 ¼ 2:52ð47Þ fm and r 0 ¼ 0:7ð1Þ fm where the errors are purely statistical. Based on these results, we discuss the possibility of a shallow bound state for the two charmed mesons within the nonrelativistic potential scattering model. It is argued that, albeit the interaction between the two charmed mesons being attractive, it is unlikely that they can form a shallow bound state in this channel. This calculation provides some useful information on the nature of the newly discovered resonancelike structure Z þ ð4430Þ by the Belle Collaboration.

Thermal properties of glueballs in SU (3) Yang-Mills theory are investigated in a large temperature range from 0.3Tc to 1.9Tc on anisotropic lattices. The glueball operators are optimized for the projection of the ground states by the variational method with a smearing scheme. Their thermal correlators are calculated in all 20 symmetry channels. It is found in all channels that the pole masses MG of glueballs remain almost constant when the temperature is approaching the critical temperature Tc from below, and start to reduce gradually with the temperature going above Tc. The correlators in the 0 ++ , 0 −+ , and 2 ++ channels are also analyzed based on the Breit-Wigner Ansatz by assuming a thermal width Γ to the pole mass ω0 of each thermal glueball ground state. While the values of ω0 are insensitive to T in the whole temperature range, the thermal widths Γ exhibit distinct behaviors at temperatures below and above Tc. The widths are very small (approximately few percent of ω0 or even smaller) when T < Tc, but grow abruptly when T > Tc and reach values of roughly Γ ∼ ω0/2 at T ≈ 1.9Tc.Thermal properties of glueballs in SU (3) Yang-Mills theory are investigated in a large temperature range from 0.3Tc to 1.9Tc on anisotropic lattices. The glueball operators are optimized for the projection of the ground states by the variational method with a smearing scheme. Their thermal correlators are calculated in all 20 symmetry channels. It is found in all channels that the pole masses MG of glueballs remain almost constant when the temperature is approaching the critical temperature Tc from below, and start to reduce gradually with the temperature going above Tc. The correlators in the 0 ++ , 0 −+ , and 2 ++ channels are also analyzed based on the Breit-Wigner Ansatz by assuming a thermal width Γ to the pole mass ω0 of each thermal glueball ground state. While the values of ω0 are insensitive to T in the whole temperature range, the thermal widths Γ exhibit distinct behaviors at temperatures below and above Tc. The widths are very small (approximately few percent of ω0 or even smaller) when T < Tc, but grow abruptly when T > Tc and reach values of roughly Γ ∼ ω0/2 at T ≈ 1.9Tc.

We study the reaction e + e − → ωπ 0 in the vicinity of φ mass region. The isospin-violating φ excitation is accounted for by two major mechanisms. One is electromagnetic (EM) transition and the other is strong isospin violations. For the latter, we consider contributions from the intermediate hadronic meson loops and φ-ρ 0 mixing as the major mechanisms via the t and s-channel transitions, respectively. By fitting the recent KLOE data, we succeed in constraining the model parameters and extracting the φ → ωπ 0 branching ratio. It shows that the branching ratio is sensitive to the φ excitation line shape and background contributions. Some crucial insights into the correlation between isospin violation and Okubo-Zweig-Iizuka (OZI) rule evading transitions are also learned.

We investigate the D "D production in e þ e À annihilations near threshold in an effective Lagrangian approach. This shows that the lineshape of the cross section near threshold is sensitive to the contributions from c 0 , though it is below the D " D threshold. The recent experimental data from the BES and Belle collaborations allow us to determine the c 0 D " D coupling constant, which appears to be consistent with other theoretical studies. As a consequence, the c 0 -c ð3770Þ mixing parameter can be extracted around the c ð3770Þ mass region. Resonance parameters for c ð3770Þ, Xð3900Þ, c ð4040Þ, and c ð4160Þ are also investigated. The Xð3900Þ appears as an enhancement at around 3.9 GeV in the Belle data. In addition to treating it as a resonance, we also study the mechanism through which the enhancement is produced by the D " D Ã þ c:c: open channel effects. Our result shows that such a possibility cannot be eliminated.

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In the J/ψ radiative decay channels J/ψ → γVV , the result of partial wave analysis indicates that the VV systems are predominately pseudoscalar component, and most of these channels have relatively large branching ratios at an order of 10 −3 . Meanwhile, vector mesons, such as ρ, ω and K * , have strong couplings with nucleons and/or hyperons. This suggests a dynamical mechanism describing the ηpp form factors for higher η mesons, such as η(1405/1475) and η(1760). It is thus natural to expect that rescatterings of these vector meson pairs into pp of 0 − partial wave could be an important source contributing to J/ψ → γpp of which the branching ratio is at the order of 10 −4 . Our calculation justifies this point. In particular, we find that interferences between different rescattering amplitudes can produce a significant threshold enhancement in the invariant mass spectrum of pp. Without introducing dramatic ingredients, our model provides a natural explanation for the peculiar threshold enhancement observed by BES-II in J/ψ → γpp. Additional experimental constraints on the VV → pp transitions are examined. This mechanism in J/ψ → ωpp is also discussed.

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