APS » Phys. Rev. D » Volume 76 » Issue 9

M. Ablikim,¹ J. Z. Bai,¹ Y. Ban,¹¹ X. Cai,¹ H. F. Chen,¹⁶ H. S. Chen,¹ H. X. Chen,¹ J. C. Chen,¹ Jin Chen,¹ Y. B. Chen,¹ Y. P. Chu,¹ Y. S. Dai,¹⁸ L. Y. Diao,⁸ Z. Y. Deng,¹ Q. F. Dong,¹⁴ S. X. Du,¹ J. Fang,¹ S. S. Fang,¹ C. D. Fu,¹⁴ C. S. Gao,¹ Y. N. Gao,¹⁴ S. D. Gu,¹ Y. T. Gu,⁴ Y. N. Guo,¹ Z. J. Guo,¹⁵ F. A. Harris,¹⁵ K. L. He,¹ M. He,¹² Y. K. Heng,¹ J. Hou,¹⁰ H. M. Hu,¹ J. H. Hu,³ T. Hu,¹ G. S. Huang,¹ X. T. Huang,¹² X. B. Ji,¹ X. S. Jiang,¹ X. Y. Jiang,⁵ J. B. Jiao,¹² D. P. Jin,¹ S. Jin,¹ Y. F. Lai,¹ G. Li,¹ H. B. Li,¹ J. Li,¹ R. Y. Li,¹ S. M. Li,¹ W. D. Li,¹ W. G. Li,¹ X. L. Li,¹ X. N. Li,¹ X. Q. Li,¹⁰ Y. F. Liang,¹³ H. B. Liao,¹ B. J. Liu,¹ C. X. Liu,¹ F. Liu,⁶ Fang Liu,¹ H. H. Liu,¹ H. M. Liu,¹ J. Liu,² J. B. Liu,¹ J. P. Liu,¹⁷ Jian Liu,¹ Q. Liu,¹⁵ R. G. Liu,¹ Z. A. Liu,¹ Y. C. Lou,⁵ F. Lu,¹ G. R. Lu,⁵ J. G. Lu,¹ C. L. Luo,⁹ F. C. Ma,⁸ H. L. Ma,² L. L. Ma,¹ Q. M. Ma,¹ Z. P. Mao,¹ X. H. Mo,¹ J. Nie,¹ S. L. Olsen,¹⁵ R. G. Ping,¹ N. D. Qi,¹ H. Qin,¹ J. F. Qiu,¹ Z. Y. Ren,¹ G. Rong,¹ X. D. Ruan,⁴ L. Y. Shan,¹ L. Shang,¹ C. P. Shen,¹⁵ D. L. Shen,¹ X. Y. Shen,¹ H. Y. Sheng,¹ H. S. Sun,¹ S. S. Sun,¹ Y. Z. Sun,¹ Z. J. Sun,¹ X. Tang,¹ G. L. Tong,¹ G. S. Varner,¹⁵ D. Y. Wang,¹ L. Wang,¹ L. L. Wang,¹ L. S. Wang,¹ M. Wang,¹ P. Wang,¹ P. L. Wang,¹ W. F. Wang,¹ Y. F. Wang,¹ Z. Wang,¹ Z. Y. Wang,¹ Zheng Wang,¹ C. L. Wei,¹ D. H. Wei,¹ Y. Weng,¹ N. Wu,¹ X. M. Xia,¹ X. X. Xie,¹ G. F. Xu,¹ X. P. Xu,⁶ Y. Xu,¹⁰ M. L. Yan,¹⁶ H. X. Yang,¹ Y. X. Yang,³ M. H. Ye,² Y. X. Ye,¹⁶ G. W. Yu,¹ C. Z. Yuan,¹ Y. Yuan,¹ S. L. Zang,¹ Y. Zeng,⁷ B. X. Zhang,¹ B. Y. Zhang,¹ C. C. Zhang,¹ D. H. Zhang,¹ H. Q. Zhang,¹ H. Y. Zhang,¹ J. W. Zhang,¹ J. Y. Zhang,¹ S. H. Zhang,¹ X. Y. Zhang,¹² Yiyun Zhang,¹³ Z. X. Zhang,¹¹ Z. P. Zhang,¹⁶ D. X. Zhao,¹ J. W. Zhao,¹ M. G. Zhao,¹ P. P. Zhao,¹ W. R. Zhao,¹ Z. G. Zhao,¹ H. Q. Zheng,¹¹ J. P. Zheng,¹ Z. P. Zheng,¹ L. Zhou,¹ K. J. Zhu,¹ Q. M. Zhu,¹ Y. C. Zhu,¹ Y. S. Zhu,¹ Z. A. Zhu,¹ B. A. Zhuang,¹ X. A. Zhuang,¹ and B. S. Zou¹

(BES Collaboration)

¹Institute of High Energy Physics, Beijing 100049, People's Republic of China
²China Center for Advanced Science and Technology (CCAST), Beijing 100080, People's Republic of China
³Guangxi Normal University, Guilin 541004, People's Republic of China
⁴Guangxi University, Nanning 530004, People's Republic of China
⁵Henan Normal University, Xinxiang 453002, People's Republic of China
⁶Huazhong Normal University, Wuhan 430079, People's Republic of China
⁷Hunan University, Changsha 410082, People's Republic of China
⁸Liaoning University, Shenyang 110036, People's Republic of China
⁹Nanjing Normal University, Nanjing 210097, People's Republic of China
¹⁰Nankai University, Tianjin 300071, People's Republic of China
¹¹Peking University, Beijing 100871, People's Republic of China
¹²Shandong University, Jinan 250100, People's Republic of China
¹³Sichuan University, Chengdu 610064, People's Republic of China
¹⁴Tsinghua University, Beijing 100084, People's Republic of China
¹⁵University of Hawaii, Honolulu, Hawaii 96822, USA
¹⁶University of Science and Technology of China, Hefei 230026, People's Republic of China
¹⁷Wuhan University, Wuhan 430072, People's Republic of China
¹⁸Zhejiang University, Hangzhou 310028, People's Republic of China

Using 58×10⁶ J/psi and 14×10⁶ psi(2S) events collected by the BESII detector at the BEPC, branching fractions or upper limits for the decays J/psi and psi(2S)-->Lambda[overline Lambda ]pi⁰ and Lambda[overline Lambda ]eta are measured. For the isospin violating decays, the upper limits are determined to be [script B](J/psi-->Lambda[overline Lambda ]pi⁰)<6.4×10^-5 and [script B][psi(2S)-->Lambda[overline Lambda ]pi⁰]<4.9×10^-5 at the 90% confidence level. The isospin conserving process J/psi-->Lambda[overline Lambda ]eta is observed for the first time, and its branching fraction is measured to be [script B](J/psi-->Lambda[overline Lambda ]eta)=(2.62±0.60±0.44)×10^-4, where the first error is statistical and the second one is systematic. No Lambda[overline Lambda ]eta signal is observed in psi(2S) decays, and [script B][psi(2S)-->Lambda[overline Lambda ]eta]<1.2×10^-4 is set at the 90% confidence level. Branching fractions of J/psi decays into Sigma⁺pi^-[overline Lambda ] and [overline Sigma ]^-pi⁺Lambda are also reported, and the sum of these branching fractions is determined to be [script B](J/psi-->Sigma⁺pi^-[overline Lambda ]+c.c.)=(1.52±0.08±0.16)×10^-3.

©2007 The American Physical Society

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