We report measurements of branching fractions for psi(2S) decays into omegapi(+)pi(-), b(1)pi, omegaf(2)(1270), omegaK(+)K(-), omegap (p) over bar, phipi(+)pi(-), phif(0)(980), phiK(+)K(-), and an upper limit for phip (p) over bar final states based on a data sample of (4.02+/-0.22)x10(6)psi(2S) events collected with the BESI detector at the Beijing Electron-Positron Collider. The branching fractions for b(1)pi and omegaf(2)(1270) update previous BES results, while those for other decay modes are first measurements. The ratios of psi(2S) and J/psi branching fractions are smaller than what is expected from the 12% rule by a factor of 5 for omegaf(2)(1270) and by a factor of 2 for omegapi(+)pi(-), omegap (p) over bar, and phiK(+)K(-), while for other studied channels the ratios are consistent with expectations within errors.

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.

The first observation of χcJ(J=0,1,2) decays to ΛΛ¯ is reported using ψ(2S) data collected with the Beijing Spectrometer detector at the Beijing Electron Positron Collider. The branching ratios are determined to be B(χc0→ΛΛ¯)=(4.7−1.2+1.3±1.0)×10−4, B(χc1→ΛΛ¯)=(2.6−0.9+1.0±0.6)×10−4 and B(χc2→ΛΛ¯)=(3.3−1.3+1.5±0.7)×10−4. The results are compared with model predictions.Received 7 April 2003DOI:https://doi.org/10.1103/PhysRevD.67.112001©2003 American Physical Society

Using a sample of 5.8×107J/ψ events, the Beijing Spectrometer experiment has searched for the decay J/ψ→eμ. Four candidates, consistent with the estimated background, are observed, and an upper limit on the branching fraction of J/ψ→eμ of 1.1×10−6 at the 90% C.L. is obtained.

The first observation of chi(cJ) (J=0,1,2) decays to Lambda(Lambda) over bar is reported using psi(2S) data collected with the Beijing Spectrometer detector at the Beijing Electron Positron Collider. The branching ratios are determined to be B(chi(c0)-->Lambda(Lambda) over bar)=(4.7(-1.2)(+1.3)+/-1.0)x10(-4), B(chi(c1)-->Lambda(Lambda) over bar)=(2.6(-0.9)(+1.0)+/-0.6)x10(-4) and B(chi(c2)-->Lambda(Lambda) over bar)=(3.3(-1.3)(+1.5)+/-0.7)x10(-4). The results are compared with model predictions.

Inclusive momentum spectra and multiplicity distributions of charged particles measured with the BESII detector at center of mass energies of 2.2, 2.6, 3.0, 3.2, 4.6 and 4.8 GeV are presented. Values of the second binomial moment, R2, obtained from the multiplicity distributions are reported. These results are compared with both experimental data from high energy ee, ep and pp̄ experiments and QCD calculations.

[1–11]. However, from a theoretical point of view, the ac-curacies of these experimental measurements are still not sufficient. For in-stance, in order to calculate the strength of the spin-spin interaction term innon-relativistic potential models, it is necessary to know precisely the massdifference between the J/ψ(1

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 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.

J. Z. Bai, Y. Ban, J. G. Bian, X. Cai, J. F. Chang, H. F. Chen, H. S. Chen, Jie Chen, J. C. Chen, Y. B. Chen, S. P. Chi, Y. P. Chu, X. Z. Cui, Y. S. Dai, L. Y. Dong, Z. Z. Du, W. Dunwoodie, J. Fang, S. S. Fang, H. Y. Fu, L. P. Fu, C. S. Gao, Y. N. Gao, M. Y. Gong, S. D. Gu, Y. N. Guo, Y. Q. Guo, Z. J. Guo, S. W. Han, F. A. Harris, J. He, K. L. He, M. He, X. He, Y. K. Heng, T. Hong, H. M. Hu, T. Hu, G. S. Huang, X. P. Huang, J. M. Izen, X. B. Ji, C. H. Jiang, X. S. Jiang, D. P. Jin, S. Jin, Y. Jin, B. D. Jones, Z. J. Ke, D. Kong, Y. F. Lai, G. Li, H. H. Li, J. Li, J. C. Li, Q. J. Li, R. Y. Li, W. Li, W. G. Li, X. Q. Li, C. F. Liu, F. Liu, H. M. Liu, J. P. Liu, R. G. Liu, T. R. Liu, Y. Liu, Z. A. Liu, Z. X. Liu, X. C. Lou, G. R. Lu, F. Lu, H. J. Lu, J. G. Lu, Z. J. Lu, X. L. Luo, E. C. Ma, F. C. Ma, J. M. Ma, R. Malchow, Z. P. Mao, X. C. Meng, X. H. Mo, J. Nie, Z. D. Nie, S. L. Olsen, D. Paluselli , H. P. Peng, F. Porter, N. D. Qi, C. D. Qian, J. F. Qiu, G. Rong, D. L. Shen, H. Shen, X. Y. Shen, H. Y. Sheng, F. Shi, H. S. Sun, S. S. Sun, Y. Z. Sun, X. Tang, D. Tian, W. Toki, G. L. Tong, G. S. Varner, J. Wang, J. Z. Wang, L. Wang, L. S. Wang, M. Wang, Meng Wang, P. Wang, P. L. Wang, W. F. Wang, Y. F. Wang, Y. Y. Wang, Z. Wang, Zheng Wang, Z. Y. Wang, C. L. Wei, N. Wu, X. M. Xia, X. X. Xie, G. F. Xu, Y. Xu, S. T. Xue, M. L. Yan, W. B. Yan, C. Y. Yang, G. A. Yang, H. X. Yang, M. H. Ye, S. W. Ye, Y. X. Ye, J. Ying, C. S. Yu, G. W. Yu, C. Z. Yuan, J. M. Yuan, Y. Yuan, Q. Yue, Y. Zeng, B. X. Zhang, B. Y. Zhang, C. C. Zhang, D. H. Zhang, H. Y. Zhang, J. Zhang, J. W. Zhang, L. Zhang, L. S. Zhang, Q. J. Zhang, S. Q. Zhang, X. Y. Zhang, Y. Y. Zhang, Yiyun Zhang, Z. P. Zhang, D. X. Zhao, Jiawei Zhao, J. W. Zhao, P. P. Zhao, W. R. Zhao, Y. B. Zhao, Z. G. Zhao, J. P. Zheng, L. S. Zheng, Z. P. Zheng, X. C. Zhong, B. Q. Zhou, G. M. Zhou, L. Zhou, K. J. Zhu, Q. M. Zhu, Y. C. Zhu, Y. S. Zhu, Z. A. Zhu, B. A. Zhuang, B. S. Zou. 1 Institute of High Energy Physics, Beijing 100039, People’s Republic of China 2 California Institute of Technology, Pasadena, California 91125 3 China Center of Advanced Science and Technology, Beijing 100080, People’s Republic of China 4 Colorado State University, Fort Collins, Colorado 80523 5 Henan Normal University, Xinxiang 453002, People’s Republic of China 6 Huazhong Normal University, Wuhan 430079, People’s Republic of China 7 Hunan University, Changsha 410082, People’s Republic of China 8 Liaoning University, Shenyang 110036, People’s Republic of China 9 Nankai University, Tianjin 300071, People’s Republic of China 10 Peking University, Beijing 100871, People’s Republic of China 11 Shandong University, Jinan 250100, People’s Republic of China 12 Shanghai Jiaotong University, Shanghai 200030, People’s Republic of China 13 Sichuan University, Chengdu 610064, People’s Republic of China 14 Stanford Linear Accelerator Center, Stanford, California 94309 15 Tsinghua University, Beijing 100084, People’s Republic of China 16 University of Hawaii, Honolulu, Hawaii 96822 17 University of Science and Technology of China, Hefei 230026, People’s Republic of China 18 University of Texas at Dallas, Richardson, Texas 75083-0688 19 Wuhan University, Wuhan 430072, People’s Republic of China 20 Zhejiang University, Hangzhou 310028, People’s Republic of China

The Beijing Spectrometer (BES) detector is a general purpose solenoid detector at the Beijing Electron Positron Collider (BEPC) in Beijing, China, that has collected large numbers of J/ψ, ψ′, Ds, D and τ events. In this paper, we describe the recent upgrade of the initial BES detector (BESI) to the improved BESII detector.

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.

The first measurement of B(D-0 --> phi X-0) and an upper limit for B(D+ --> phi X+) are determined from 22.3 pb(-1) of e(+)e(-) annihilation data at a c.m. energy of 4.03 GeV. The data were recorded by the Beijing Spectrometer (BES) at BEPC. A recoil charge method is applied to charm threshold data to determine the charge of the D meson in the recoil from 9054+/-309+/-416 reconstructed D-0, D+ mesons. The branching fractions B(D0 --> phi X-0) = (1.71(-0.71)(+0.76) +/- 0.17)%, and B(D+ --> phi X+) < 1.8% are determined from 10 events with a reconstructed D and a recoiling phi. In addition, a 90% C.L. upper limit of B(D+ --> phi e(+)X(0)) < 1.6% is determined from a search for semileptonic decays of the D+.

Using the upgraded Beijing Spectrometer we have measured the total cross section for e(+) e(-) annihilation into hadronic final states at center-of-mass energies of 2.6, 3.2,.3.4, 3.55, 4.6, and 5.0 GeV. Values of R, sigma(e(+)e(-) --> hadrons)/sigma(e(+)e(-) --> mu(+)mu(-)), are determined.