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arXiv · 1208.1461

Evidence for $η_{c} \rightarrow γγ$ and Measurement of $J/ψ\rightarrow 3γ$

BESIII Collaboration·M. Ablikim·M. N. Achasov·D. J. Ambrose·F. F. An·Q. An·Z. H. An·J. Z. Bai·Y. Ban·J. Becker·M. Bertani·J. M. Bian·E. Boger·O. Bondarenko·I. Boyko·R. A. Briere·V. Bytev·X. Cai·O. Cakir·A. Calcaterra·G. F. Cao·S. A. Cetin·J. F. Chang·G. Chelkov·G. Chen·H. S. Chen·J. C. Chen·M. L. Chen·S. J. 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·R. B. Ferroli·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·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. 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·C. H. Li·Cheng Li
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Abstract

The decay of $J/ψ$ to three photons is studied using $ψ(3686)\toπ^+π^-J/ψ$ in a sample of $1.0641\times10^8$ $ψ(3686)$ events collected with the BESIII detector. Evidence of the direct decay of $η_c$ to two photons, $η_c\toγγ$, is reported, and the product branching fraction is determined to be $\mathcal{B}(J/ψ\toγη_c,η_c\to γγ)=(4.5\pm1.2\pm0.6)\times10^{-6}$, where the first error is statistical and the second is systematic. The branching fraction for $J/ψ\to3γ$ is measured to be $(11.3\pm1.8\pm2.0)\times 10^{-6}$ with improved precision.

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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, Y. Ban, J. Becker, M. Bertani, J. M. Bian, E. Boger, O. Bondarenko, I. Boyko, R. A. Briere, V. Bytev, X. Cai, O. Cakir, A. Calcaterra, G. F. Cao, S. A. Cetin, J. F. Chang, G. Chelkov, G. Chen, H. S. Chen, J. C. Chen, M. L. Chen, S. J. 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, R. B. Ferroli, 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, 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. 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, C. H. Li, Cheng Li. 2013-02-06. Evidence for $η_{c} \rightarrow γγ$ and Measurement of $J/ψ\rightarrow 3γ$. https://doi.org/10.1103/physrevd.87.032003

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