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arXiv · 1612.05721

Observation of the doubly radiative decay $η^{\prime}\to γγπ^0$

BESIII Collaboration·M. Ablikim·M. N. Achasov·S. Ahmed·X. C. Ai·O. Albayrak·M. Albrecht·D. J. Ambrose·A. Amoroso·F. F. An·Q. An·J. Z. Bai·O. Bakina·R. Baldini Ferroli·Y. Ban·D. W. Bennett·J. V. Bennett·N. Berger·M. Bertani·D. Bettoni·J. M. Bian·F. Bianchi·E. Boger·I. Boyko·R. A. Briere·H. Cai·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. Chen·S. J. Chen·X. Chen·X. R. Chen·Y. B. Chen·X. K. Chu·G. Cibinetto·H. L. Dai·J. P. Dai·A. Dbeyssi·D. Dedovich·Z. Y. Deng·A. Denig·I. Denysenko·M. Destefanis·F. De Mori·Y. Ding·C. Dong·J. Dong·L. Y. Dong·M. Y. Dong·Z. L. Dou·S. X. Du·P. F. Duan·J. Z. Fan·J. Fang·S. S. Fang·X. Fang·Y. Fang·R. Farinelli·L. Fava·F. Feldbauer·G. Felici·C. Q. Feng·E. Fioravanti·M. Fritsch·C. D. Fu·Q. Gao·X. L. Gao·Y. Gao·Z. Gao·I. Garzia·K. Goetzen·L. Gong·W. X. Gong·W. Gradl·M. Greco·M. H. Gu·Y. T. Gu·Y. H. Guan·A. Q. Guo·L. B. Guo·R. P. Guo·Y. Guo·Y. P. Guo·Z. Haddadi·A. Hafner·S. Han·X. Q. Hao·F. A. Harris·K. L. He·F. H. Heinsius·T. Held
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Abstract

Based on a sample of $1.31$ billion $J/ψ$ events collected with the BESIII detector, we report the study of the doubly radiative decay $η^\prime\to γγπ^0$ for the first time, where the $η^\prime$ meson is produced via the $J/ψ\to γη^\prime$ decay. The branching fraction of $η^\prime\to γγπ^0$ inclusive decay is measured to be ${\cal B}(η^\prime\to γγπ^0)_{\text{Incl.}}$ = $(3.20\pm0.07\mbox{(stat)}\pm0.23\mbox{(sys)})\times 10^{-3}$, while the branching fractions of the dominant process $η^\prime\rightarrowγω$ and the non-resonant component are determined to be ${\cal B}(η^\prime\to γω)\times {\cal B}(ω\to γπ^0) = (23.7 \pm1.4\mbox{(stat)}\pm1.8\mbox{(sys)})\times 10^{-4}$ and ${\cal B}(η^\prime\to γγπ^0)_{\text{NR}} = (6.16\pm0.64\mbox{(stat)} \pm0.67\mbox{(sys)})\times 10^{-4}$, respectively. In addition, the $M^2_{γγ}$-dependent partial widths of the inclusive decay are also presented.

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BESIII Collaboration, M. Ablikim, M. N. Achasov, S. Ahmed, X. C. Ai, O. Albayrak, M. Albrecht, D. J. Ambrose, A. Amoroso, F. F. An, Q. An, J. Z. Bai, O. Bakina, R. Baldini Ferroli, Y. Ban, D. W. Bennett, J. V. Bennett, N. Berger, M. Bertani, D. Bettoni, J. M. Bian, F. Bianchi, E. Boger, I. Boyko, R. A. Briere, H. Cai, 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. Chen, S. J. Chen, X. Chen, X. R. Chen, Y. B. Chen, X. K. Chu, G. Cibinetto, H. L. Dai, J. P. Dai, A. Dbeyssi, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, C. Dong, J. Dong, L. Y. Dong, M. Y. Dong, Z. L. Dou, S. X. Du, P. F. Duan, J. Z. Fan, J. Fang, S. S. Fang, X. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, E. Fioravanti, M. Fritsch, C. D. Fu, Q. Gao, X. L. Gao, Y. Gao, Z. Gao, I. Garzia, K. Goetzen, L. Gong, W. X. Gong, W. Gradl, M. Greco, M. H. Gu, Y. T. Gu, Y. H. Guan, A. Q. Guo, L. B. Guo, R. P. Guo, Y. Guo, Y. P. Guo, Z. Haddadi, A. Hafner, S. Han, X. Q. Hao, F. A. Harris, K. L. He, F. H. Heinsius, T. Held. 2017-08-03. Observation of the doubly radiative decay $η^{\prime}\to γγπ^0$. https://doi.org/10.1103/physrevd.96.012005

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