Radiative decays of the radially excited charmonium resonance, \psi(2S), into \pi\pi, K Kbar and \eta\eta final states have been measured in a sample of 3.96 * 10^6 \psi(2S) events collected by the BES collaboration. The branching ratios B(\psi(2S) ->\gamma f_{2}(1270)) = (2.27 +- 0.26 +- 0.39) * 10^{-4} and B(\psi(2S) ->\gamma f_0(1710)) * B(f_0(1710) ->K^+ K^-) = (5.59 +- 1.12 +- 0.93) * 10^{-5} are obtained. When compared to the corresponding radiative J/\psi decays, the observed \psi(2S) radiative decay rates into \gamma f_2(1270) and \gamma f_0(1710) are consistent with the 15% rule.

With 7.8 million produced J/psi events collected by the BES detector at the BEPC, the decay J/psi-->Sigma(0)Sigma(0) is analysed. The branching ratio is measured to be BR(J/psi-->Sigma(0)Sigma(0)) = (0.97 +/- 0.04 +/- 0.24) x 10(-3). The angular distribution is of the form dN/dcostheta = N-0(1 + alphacos(2)theta) with alpha value of -0.21 +/- 0.27 +/- 0.13.

The branching fraction of the psi(2S) decay into tau(+) tau(-) has been measured for the first time using the BES detector at the Beijing Electron-Positron Collider. The result is B-tautau =(2.71+/-0.43+/-0.55) x 10(-3), where the first error is statistical and the second is systematic. This value, along with those for the branching fractions into e(+)c(-) and mu(+)mu(-) of this resonance, satisfy well the relation predicted by the sequential lepton hypothesis. Combining all these values with the leptonic width of the resonance, the total width of the psi(2S) is determined to be (252+/-37) keV.

We report a measurement of the absolutely inclusive semileptonic branching fractions of D- and (D-0) over bar mesons, using a data sample of 22.3 pb(-1) collected with BES detector at BEPC e(+) e Collider at roots = 4.03 GeV and based on the method of combinative D+ and D-0 single and double tags. The measured values of the branching fractions for D- --> e(-) X and (D-0) over bar --> e(-) X are ( 21.8 +/- 8.5 +/- 4.2)% and (8.9 +/- 3.0 +/- 1.6)%, respectively. The measured ratio of the branching fractions is BF(D- --> e(-) X)/BF (D0 --> e (-) X) -2.4 +/- 1.7 +/- 0.8.

We report values of R = sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->mu(+)mu(-)) for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.

Data are presented on the reaction J/psi -->> using 7.8 x 10(6) J/psi triggers collected by the BEjing Spectrometer (BES). A partial wave analysis is performed. A clear enhancement near the p eta((p) over bar eta) threshold is observed. It is fitted with a J(P) = 1/2(-) resonance with mass M = 1530 +/- 10 MeV and width Gamma = 95 +/- 25 MeV. In addition, there is a peak around 1650 MeV with J(P) = 1/2(-) preferred also, fitted with M = 1637 +/- 20 MeV and Gamma = 145(-45)(+80) MeV. These two N* resonances are believed to be the two well established states, S-11(1535) and S-11(1650). respectively. It is the first partial wave study of the production of these resonances from J/psi decays. (C) 2001 Published by Elsevier Science B.V.

Data are presented on the reaction J/ψ→pp̄η using 7.8×106J/ψ triggers collected by the BEjing Spectrometer (BES). A partial wave analysis is performed. A clear enhancement near the pη(p̄η) threshold is observed. It is fitted with a JP=12− resonance with mass M=1530±10 MeV and width Γ=95±25 MeV. In addition, there is a peak around 1650 MeV with JP=12− preferred also, fitted with M=1647±20 MeV and Γ=145+80−45 MeV. These two N∗ resonances are believed to be the two well established states, S11(1535) and S11(1650), respectively. It is the first partial wave study of the production of these resonances from J/ψ decays.

A sample of 3.95M psi (2S) decays registered in the BES detector are used to study final states containing pairs of octet and decuplet baryons. We report branching fractions for psi (2S)--> p(p) over bar, (Lambda )over bar>, Sigma (0) )over bar>(0), Xi (-) )over bar>(+) Delta (++) )over bar>(--), Sigma (+)(1385) )over bar>(-)(1385). Xi (0)(1530) )over bar>(0)(1530). and Omega (-) )over bar>(+). These results are compared to expectations based on the SU(3)-flavor symmetry, factorization. and perturbative QCD.

BES data on J/psi-> gamma(K(+/-)K(S)(0)pi double dagger) are presented. There is a strong peak due to eta(1440)/iota, which is fitted with a Breit-Wigner amplitude with s-dependent widths for decays to K * K, kappa K, eta pi pi and rho rho: kappa refers to the K pi S-wave. At a mass of similar to 2040 MeV, there is a second peak with width similar to 400 MeV; J(P) = 0(-) is preferred over 1(+) and 2(-) respectively by 5.2 and 6.8 standard deviations. It is a possible candidate for a 0(-) s(s) over bar g hybrid partner of pi(1800). (C) 2000 Published by Elsevier Science B.V. All rights reserved.

Based on 7.8 x 10(6) J/psi events collected by BES experiment, J/psi radiative decay J/psi-->gamma gamma V(rho, phi) have been studied. The eta(1430) resonance has been observed in these two channels respectively. Its mass,width and branching ratio are 1431 +/- 17MeV, 88 +/- 28MeV, and Br (J/psi-->gamma eta(1430)) Br(eta(1430)-->gamma rho) = (1.1 +/- 0.5 +/- 0.3) x 10(-4) from J/psi-->gamma gamma rho mode,1424 +/- 15MeV, 73 +/- 58MeV, and Br(J/psi-->gamma eta(1430)) Br(eta(1430)-->gamma phi) = (2.0 +/- 1.0 +/- 0.6) x 10(-4) from J/psi-->gamma gamma phi mode.

In a sample of 7.8 million J/psi decays collected in the Beijing Spectrometer, the process J/psi --> gamma eta(c) is observed for live different eta(c) decay channels: K+ K- pi(+)pi(-), pi(+)pi(-)pi(+)pi(-), K+/- K(s)(o)pi(-/+) (with K-s(o) --> pi(+)pi(-)), phi phi (with phi-->K+K-) and K(+)K(-)pi(o). From these signals, we determine the mass of eta(c) to be 2976.6+/-2.9 +/- 1.3 MeV. Combining this result with a previously reported result from a similar study using psi(2S)-->gamma eta(c) detected in the same spectrometer gives m(eta c) = 2976.3 +/- 2.3 +/- 1.2 MeV. For the combined samples, we obtain Gamma(eta c) = 11.0 +/- 8.1 +/- 4.1 MeV.

BES data on J/psi --> gamma(pi(+) pi(-) pi(+) pi(-)) have been analyzed into partial waves. We fit with resonances having J(PC) = 2(++) at 1275 MeV, 0(++) at 1500 MeV, 2(++) at 1565 MeV, 0(++) at 1740 MeV, 2(++) at 1940 MeV and 0(++) at 2104 MeV, plus a broad 0(-) component. The 0(++) resonances decay dominantly to sigma sigma, while 2(++) resonances in the high mass region decay mainly to f(2)(1270)sigma and sigma sigma; 2(++) resonances from the low mass region decay dominantly to rho rho. (C) 2000 Published by Elsevier Science B.V. All rights reserved.