APS » Phys. Rev. Lett. » Volume 97 » Issue 6

M. Ablikim,¹ J. Z. Bai,¹ Y. Ban,¹⁰ J. G. Bian,¹ X. Cai,¹ J. F. Chang,¹ H. F. Chen,¹⁶ H. S. Chen,¹ H. X. Chen,¹ J. C. Chen,¹ Jin Chen,¹ Jun Chen,⁶ M. L. Chen,¹ Y. B. Chen,¹ S. P. Chi,² Y. P. Chu,¹ X. Z. Cui,¹ H. L. Dai,¹ Y. S. Dai,¹⁸ Z. Y. Deng,¹ L. Y. Dong,¹ S. X. Du,¹ Z. Z. Du,¹ J. Fang,¹ S. S. Fang,² C. D. Fu,¹ H. Y. Fu,¹ C. S. Gao,¹ Y. N. Gao,¹⁴ M. Y. Gong,¹ W. X. Gong,¹ S. D. Gu,¹ Y. N. Guo,¹ Y. Q. Guo,¹ Z. J. Guo,¹⁵ F. A. Harris,¹⁵ K. L. He,¹ M. He,¹¹ X. He,¹ Y. K. Heng,¹ H. M. Hu,¹ T. Hu,¹ G. S. Huang,¹ L. Huang,⁶ X. P. Huang,¹ X. B. Ji,¹ Q. Y. Jia,¹⁰ C. H. Jiang,¹ X. S. Jiang,¹ D. P. Jin,¹ S. Jin,¹ Y. Jin,¹ Y. F. Lai,¹ F. Li,¹ G. Li,¹ H. B. Li,¹ H. H. Li,¹ J. Li,¹ J. C. Li,¹ Q. J. Li,¹ R. B. Li,¹ R. Y. Li,¹ S. M. Li,¹ W. G. Li,¹ X. L. Li,⁷ X. Q. Li,⁹ X. S. Li,¹⁴ Y. F. Liang,¹³ H. B. Liao,⁵ C. X. Liu,¹ F. Liu,⁵ Fang Liu,¹⁶ H. M. Liu,¹ J. B. Liu,¹ J. P. Liu,¹⁷ R. G. Liu,¹ Z. A. Liu,¹ Z. X. Liu,¹ F. Lu,¹ G. R. Lu,⁴ J. G. Lu,¹ C. L. Luo,⁸ X. L. Luo,¹ F. C. Ma,⁷ J. M. Ma,¹ L. L. Ma,¹¹ Q. M. Ma,¹ X. Y. Ma,¹ Z. P. Mao,¹ X. H. Mo,¹ J. Nie,¹ Z. D. Nie,¹ S. L. Olsen,¹⁵ H. P. Peng,¹⁶ N. D. Qi,¹ C. D. Qian,¹² H. Qin,⁸ J. F. Qiu,¹ Z. Y. Ren,¹ G. Rong,¹ L. Y. Shan,¹ L. Shang,¹ D. L. Shen,¹ X. Y. Shen,¹ H. Y. Sheng,¹ F. Shi,¹ X. Shi,¹⁰ H. S. Sun,¹ S. S. Sun,¹⁶ Y. Z. Sun,¹ Z. J. Sun,¹ X. Tang,¹ N. Tao,¹⁶ Y. R. Tian,¹⁴ G. L. Tong,¹ G. S. Varner,¹⁵ D. Y. Wang,¹ J. X. Wang,¹ J. Z. Wang,¹ K. Wang,¹⁶ L. Wang,¹ L. S. Wang,¹ M. Wang,¹ P. Wang,¹ P. L. Wang,¹ S. Z. Wang,¹ W. F. Wang,¹ Y. F. Wang,¹ Zhe Wang,¹ Z. Wang,¹ Zheng Wang,¹ Z. Y. Wang,¹ C. L. Wei,¹ D. H. Wei,³ N. Wu,¹ Y. M. Wu,¹ X. M. Xia,¹ X. X. Xie,¹ B. Xin,⁷ G. F. Xu,¹ H. Xu,¹ Y. Xu,¹ S. T. Xue,¹ M. L. Yan,¹⁶ F. Yang,⁹ H. X. Yang,¹ J. Yang,¹⁶ S. D. Yang,¹ Y. X. Yang,³ M. Ye,¹ M. H. Ye,² Y. X. Ye,¹⁶ L. H. Yi,⁶ Z. Y. Yi,¹ C. S. Yu,¹ G. W. Yu,¹ C. Z. Yuan,¹ J. M. Yuan,¹ Y. Yuan,¹ Q. Yue,¹ S. L. Zang,¹ Yu. Zeng,¹ Y. Zeng,⁶ B. X. Zhang,¹ B. Y. Zhang,¹ C. C. Zhang,¹ D. H. Zhang,¹ H. Y. Zhang,¹ J. Zhang,¹ J. Y. Zhang,¹ J. W. Zhang,¹ L. S. Zhang,¹ Q. J. Zhang,¹ S. Q. Zhang,¹ X. M. Zhang,¹ X. Y. Zhang,¹¹ Y. J. Zhang,¹⁰ Y. Y. Zhang,¹ Yiyun Zhang,¹³ Z. P. Zhang,¹⁶ Z. Q. Zhang,⁴ D. X. Zhao,¹ J. B. Zhao,¹ J. W. Zhao,¹ M. G. Zhao,⁹ P. P. Zhao,¹ W. R. Zhao,¹ X. J. Zhao,¹ Y. B. Zhao,¹ Z. G. Zhao,¹ H. Q. Zheng,¹⁰ J. P. Zheng,¹ L. S. Zheng,¹ Z. P. Zheng,¹ X. C. Zhong,¹ B. Q. Zhou,¹ G. M. Zhou,¹ L. Zhou,¹ N. F. Zhou,¹ K. J. Zhu,¹ Q. M. Zhu,¹ Y. C. Zhu,¹ Y. S. Zhu,¹ Yingchun Zhu,¹ Z. A. Zhu,¹ B. A. Zhuang,¹ and B. S. Zou.¹

(BES Collaboration)

¹Institute of High Energy Physics, Beijing 100039, 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
⁴Henan Normal University, Xinxiang 453002, People's Republic of China
⁵Huazhong Normal University, Wuhan 430079, People's Republic of China
⁶Hunan University, Changsha 410082, People's Republic of China
⁷Liaoning University, Shenyang 110036, People's Republic of China
⁸Nanjing Normal University, Nanjing 210097, People's Republic of China
⁹Nankai University, Tianjin 300071, People's Republic of China
¹⁰Peking University, Beijing 100871, People's Republic of China
¹¹Shandong University, Jinan 250100, People's Republic of China
¹²Shanghai Jiaotong University, Shanghai 200030, 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

The decay J/N provides an effective isospin 1/2 filter for the N system due to isospin conservation. Using 58×10⁶ J/ decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/p^-+c.c. events are obtained. Besides the two well-known N^* peaks at around 1500 MeV/c² and 1670 MeV/c², there are two new, clear N^* peaks in the p invariant mass spectrum around 1360 MeV/c² and 2030 MeV/c² with statistical significance of 11 and 13, respectively. We identify these as the first direct observation of the N^*(1440) peak and a long-sought missing N^* peak above 2 GeV/c² in the N invariant mass spectrum.

©2006 The American Physical Society

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