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arXiv · 1205.4284

Two-photon widths of the $χ_{c0, 2}$ states and helicity analysis for $χ_{c2}\arγγ$}

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

Based on a data sample of 106 M $ψ^{\prime}$ events collected with the BESIII detector, the decays $ψ^{\prime}\arγχ_{c0, 2}$,$χ_{c0, 2}\arγγ$ are studied to determine the two-photon widths of the $χ_{c0, 2}$ states. The two-photon decay branching fractions are determined to be ${\cal B}(χ_{c0}\arγγ) = (2.24\pm 0.19\pm 0.12\pm 0.08)\times 10^{-4}$ and ${\cal B}(χ_{c2}\arγγ) = (3.21\pm 0.18\pm 0.17\pm 0.13)\times 10^{-4}$. From these, the two-photon widths are determined to be $Γ_{γγ}(χ_{c0}) = (2.33\pm0.20\pm0.13\pm0.17)$ keV, $Γ_{γγ}(χ_{c2}) = (0.63\pm0.04\pm0.04\pm0.04)$ keV, and $\cal R$ $=Γ_{γγ}(χ_{c2})/Γ_{γγ}(χ_{c0})=0.271\pm 0.029\pm 0.013\pm 0.027$, where the uncertainties are statistical, systematic, and those from the PDG ${\cal B}(ψ^{\prime}\arγχ_{c0,2})$ and $Γ(χ_{c0,2})$ errors, respectively. The ratio of the two-photon widths for helicity $λ=0$ and helicity $λ=2$ components in the decay $χ_{c2}\arγγ$ is measured for the first time to be $f_{0/2} =Γ^{λ=0}_{γγ}(χ_{c2})/Γ^{λ=2}_{γγ}(χ_{c2}) = 0.00\pm0.02\pm0.02$.

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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. 2012-05-19. Two-photon widths of the $χ_{c0, 2}$ states and helicity analysis for $χ_{c2}\arγγ$}. https://doi.org/10.1103/physrevd.85.112008

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