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arXiv · 1205.1036

Study of $J/ψ\to p\bar{p}$ and $J/ψ\to n\bar{n}$

BESIII Collaboration·M. Ablikim·M. N. Achasov·D. J. Ambrose·F. F. An·Q. An·Z. H. An·J. Z. Bai·R. B. Ferroli·Y. Ban·J. Becker·N. Berger·M. B. Bertani·J. M. Bian·E. Boger·O. Bondarenko·I. Boyko·R. A. Briere·V. Bytev·X. Cai·A. C. Calcaterra·G. F. Cao·J. F. Chang·G. Chelkov·G. Chen·H. S. Chen·J. C. Chen·M. L. Chen·S. J. Chen·Y. Chen·Y. B. Chen·H. P. Cheng·Y. P. Chu·D. Cronin-Hennessy·H. L. Dai·J. P. Dai·D. Dedovich·Z. Y. Deng·A. Denig·I. Denysenko·M. Destefanis·W. M. Ding·Y. Ding·L. Y. Dong·M. Y. Dong·S. X. Du·J. Fang·S. S. Fang·L. Fava·F. Feldbauer·C. Q. Feng·C. D. Fu·J. L. Fu·Y. Gao·C. Geng·K. Goetzen·W. X. Gong·W. Gradl·M. Greco·M. H. Gu·Y. T. Gu·Y. H. Guan·A. Q. Guo·L. B. Guo·Y. P. Guo·Y. L. Han·X. Q. Hao·F. A. Harris·K. L. He·M. He·Z. Y. He·T. Held·Y. K. Heng·Z. L. Hou·H. M. Hu·J. F. Hu·T. Hu·B. Huang·G. M. Huang·J. S. Huang·X. T. Huang·Y. P. Huang·T. Hussain·C. S. Ji·Q. Ji·X. B. Ji·X. L. Ji·L. K. Jia·L. L. Jiang·X. S. Jiang·J. B. Jiao·Z. Jiao·D. P. Jin·S. Jin·F. F. Jing·N. Kalantar-Nayestanaki·M. Kavatsyuk·W. Kuehn·W. Lai·J. S. Lange
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Abstract

The decays $J/ψ\to p\bar{p}$ and $J/ψ\to n\bar{n}$ have been investigated with a sample of 225.2 million $J/ψ$ events collected with the BESIII detector at the BEPCII $e^+e^-$ collider. The branching fractions are determined to be $\mathcal{B}(J/ψ\to p\bar{p})=(2.112\pm0.004\pm0.031)\times10^{-3}$ and $\mathcal{B}(J/ψ\to n\bar{n})=(2.07\pm0.01\pm0.17)\times10^{-3}$. Distributions of the angle $θ$ between the proton or anti-neutron and the beam direction are well described by the form $1+α\cos^2θ$, and we find $α=0.595\pm0.012\pm0.015$ for $J/ψ\to p\bar{p}$ and $α=0.50\pm0.04\pm0.21$ for $J/ψ\to n\bar{n}$. Our branching-fraction results suggest a large phase angle between the strong and electromagnetic amplitudes describing the $J/ψ\to N\bar{N}$ decay.

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BESIII Collaboration, M. Ablikim, M. N. Achasov, D. J. Ambrose, F. F. An, Q. An, Z. H. An, J. Z. Bai, R. B. Ferroli, Y. Ban, J. Becker, N. Berger, M. B. Bertani, J. M. Bian, E. Boger, O. Bondarenko, I. Boyko, R. A. Briere, V. Bytev, X. Cai, A. C. Calcaterra, G. F. Cao, J. F. Chang, G. Chelkov, G. Chen, H. S. Chen, J. C. Chen, M. L. Chen, S. J. Chen, Y. Chen, Y. B. Chen, H. P. Cheng, Y. P. Chu, D. Cronin-Hennessy, H. L. Dai, J. P. Dai, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, W. M. Ding, Y. Ding, L. Y. Dong, M. Y. Dong, S. X. Du, J. Fang, S. S. Fang, L. Fava, F. Feldbauer, C. Q. Feng, C. D. Fu, J. L. Fu, Y. Gao, C. Geng, K. Goetzen, W. X. Gong, W. Gradl, M. Greco, M. H. Gu, Y. T. Gu, Y. H. Guan, A. Q. Guo, L. B. Guo, Y. P. Guo, Y. L. Han, X. Q. Hao, F. A. Harris, K. L. He, M. He, Z. Y. He, T. Held, Y. K. Heng, Z. L. Hou, H. M. Hu, J. F. Hu, T. Hu, B. Huang, G. M. Huang, J. S. Huang, X. T. Huang, Y. P. Huang, T. Hussain, C. S. Ji, Q. Ji, X. B. Ji, X. L. Ji, L. K. Jia, L. L. Jiang, X. S. Jiang, J. B. Jiao, Z. Jiao, D. P. Jin, S. Jin, F. F. Jing, N. Kalantar-Nayestanaki, M. Kavatsyuk, W. Kuehn, W. Lai, J. S. Lange. 2012-08-09. Study of $J/ψ\to p\bar{p}$ and $J/ψ\to n\bar{n}$. https://doi.org/10.1103/physrevd.86.032014

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