A . Direct Measurement of the Pseudoscalar Decay Constant , fo , * _


The Beijing Spectrometer (BES) p ex eriment has observed purely leptonic decays of the D, meson in the reaction e+e+ D$D; at a c.m. energy of 4.03 GeV. Three events are observed in which one D, decays hadronically to +r, li*“K, or K”li, and the other decays leptonically to ova or l-v,. With the assumption of p-r universality, values of the branching fraction Br(D, + PV~) = 1.5?~:~+~:~ %, and the D, pseudoscalar decay constant, f& = 4.3$;:;f;:; x lo2 MeV, are obtained. Submitted to Physical Review Letters *Work supported in part by the National Natural Science Foundation of China under Contract _ No. 19290400 and the Chinese Academy of Sciences under contract No. KJ85 (IHEP); by the Department of Energy under Contract Nos. DE-FG02-91ER40676 (Boston University), DE-FGOS92ER40701 (Caltech), DE-FG03-93ER40788 (Colorado State University), DE-AC02-76ER03069 (MIT), DE-AC03-76SF00515 (SLAC), DE-FG03-91ER40679 (UC Irvine), DE-FG03-94ER40833 (U Hawaii), DE-FG05-92ER40736 (UT Dallas), DE-AC35-89ER40486 (SSC Lab); by the U.S. National Science Foundation, Grant No. PHY9203212 (U niversity of Washington); and by the Texas National Research Laboratory Commission under Contract Nos. RGFYSlB5, RGFY92B5 (Colorado State), and RCFY93-316H (UT Dallas). tpresent address: Stanford Linear Accelerator Center, Stanford, California 94309.

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@inproceedings{Chen1995AD, title={A . Direct Measurement of the Pseudoscalar Decay Constant , fo , * _}, author={Gao Peng Chen and H. F. Chen and J. Chen and S. J. Chen and S. M. Chen and Y. Chen and Y. B. Chen and Y. Q. Chen and Brenda Ss Cheng and Robin Cowan and Hannah Cui and Xue Zhe Cui and Hualin L Ding and Z. Z. Du and WILLIAM M. DUNWOODIE and X. Fan and J. Fang and .r and Michael J. Fero and C. Gao and Min Gao and Song Gao and W. Gao and Paolo Gratton and Il and Jian Hua Gu and Sang Dang Gu and W. Gu and Yi fei Gu and Y. Guo and S. W. Han and Y. Han and Frederick A. Harris and Guan Hu and H. Hu and T. Hu and X. Hu and Daisy Q Huang and Y. Huang and Joseph M. Izen and ir and Qi Peng Jia and Cai Hong Jiang and Y. Jin and Lenny Jones and Seok-Joong Kang and Michael H. Kelsey and B. K. Kim and ri and Yi Feng Lai and He-kui Lan and Peter F. Lang and Andrew James Lankford and R. Li and Huawei Li and W. D. Li and X. Li and Shinn Zong Lin and H. M. Liu and J. H. Liu and Qiao Quan Liu and R. Liu and Yi Liu and Zhiqiang Liu and Xiaoxia Lou and ll and Bradley Lowery and ‘l and Jun Lu and Angie Mejia MA and Eddie C.Y. Ma and J. Ma and Hong-bo Mao and Da Leng Shen and H. Shen and Xiao-Yan Shen and Huan-yuan Sheng and Heng Zhen Shi and X. Shi and Xiang Fen Song and H. Sun and S.-Yuh Sun and Jan Traeger Synodinos and Y. Tan and Fuqiang Wang and L. S. Wang and L. Z. Wang and ’ M. Wang and Ping Wang and S. M. Wang and T. Wang and W. Wang and Yao Wang and Stuart Whittaker and X. Xia and Ping Xie and D. Xu and Run Sheng Xu and Z. Xu and Wang Guang Yan and C. Yang and C. Y. Yang and Hai Bo Yao and M. H. Ye and Sheng Zhi Ye and C. S. Yu and C. Yu and Z. Q. Yu and Changzheng Yuan and B. Y. Zhang and Cheng Zhang and D. Zhang and Haiming Zhang and Juan Zhang and J. W. Zhang and L. Zhang and S. Zhang and Y. Zhang and D. X. Zhao and J. Zhao and M. Zhao and Peter DeYong Zhao and W. Zhao and Wayne Xin Zhao and J. Zheng and Lan Zheng and Z. Zheng}, year={1995} }