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arXiv · 2208.04477

Measurement of two-photon decay width of $\chi_{c2}(1P)$ in $ \gamma \gamma \rightarrow \chi_{c2}(1P) \rightarrow J/\psi\gamma$ at Belle

The Belle Collaboration·Y. Seino·K. Hayasaka·S. Uehara·I. Adachi·H. Aihara·S. Al Said·D. M. Asner·H. Atmacan·T. Aushev·R. Ayad·V. Babu·S. Bahinipati·P. Behera·K. Belous·J. Bennett·M. Bessner·V. Bhardwaj·B. Bhuyan·T. Bilka·D. Bodrov·G. Bonvicini·J. Borah·A. Bozek·M. Bračko·P. Branchini·T. E. Browder·A. Budano·M. Campajola·D. Červenkov·M. -C. Chang·P. Chang·V. Chekelian·A. Chen·B. G. Cheon·K. Chilikin·H. E. Cho·K. Cho·S. -J. Cho·S. -K. Choi·Y. Choi·S. Choudhury·D. Cinabro·S. Das·G. De Pietro·R. Dhamija·F. Di Capua·J. Dingfelder·Z. Doležal·T. V. Dong·D. Epifanov·T. Ferber·D. Ferlewicz·B. G. Fulsom·R. Garg·V. Gaur·N. Gabyshev·A. Garmash·A. Giri·P. Goldenzweig·E. Graziani·C. Hadjivasiliou·H. Hayashii·W. -S. Hou·C. -L. Hsu·K. Inami·N. Ipsita·A. Ishikawa·R. Itoh·M. Iwasaki·W. W. Jacobs·E. -J. Jang·S. Jia·Y. Jin·K. K. Joo·H. Kakuno·K. H. Kang·G. Karyan·T. Kawasaki·C. Kiesling·C. H. Kim·D. Y. Kim·K. -H. Kim·Y. -K. Kim·P. Kodyš·T. Konno·A. Korobov·S. Korpar·E. Kovalenko·P. Križan·P. Krokovny·M. Kumar·R. Kumar·K. Kumara·T. Lam·J. S. Lange·S. C. Lee·C. H. Li·J. Li·L. K. Li
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Abstract

We report the measurement of the two-photon decay width of $\chi_{c2}(1P)$ in two-photon processes at the Belle experiment. We analyze the process $ \gamma \gamma \rightarrow \chi_{c2}(1P) \rightarrow J/\psi\gamma$, $J/\psi \rightarrow \ell^{+} \ell^{-}$ $(\ell = e \ {\rm or} \ \mu)$ using a data sample of 971 fb$^{-1}$ collected with the Belle detector at the KEKB $e^{+} e^{-}$ collider. In this analysis, the product of the two-photon decay width of $\chi_{c2}(1P)$ and the branching fraction is determined to be $\Gamma_{\gamma \gamma}(\chi_{c2}(1P)) \mathcal{B}( \chi_{c2}(1P) \rightarrow J/\psi \, \gamma )\mathcal{B}( J/\psi \rightarrow \ell^+\ell^- ) = {\rm 14.8}$ $\pm$ ${\rm 0.3}({\rm stat.})$ $\pm$ ${\rm 0.7}({\rm syst.})$ eV, which corresponds to $ \Gamma_{\gamma \gamma}(\chi_{c2}(1P)) $ = 653 $\pm$ 13(stat.) $\pm$ 31(syst.) $\pm$ 17(B.R.) eV, where the third uncertainty is from $\mathcal{B}( \chi_{c2}(1P) \rightarrow J/\psi \, \gamma )$ and $\mathcal{B}( J/\psi \rightarrow \ell^+\ell^- )$.

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The Belle Collaboration, Y. Seino, K. Hayasaka, S. Uehara, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. Behera, K. Belous, J. Bennett, M. Bessner, V. Bhardwaj, B. Bhuyan, T. Bilka, D. Bodrov, G. Bonvicini, J. Borah, A. Bozek, M. Bračko, P. Branchini, T. E. Browder, A. Budano, M. Campajola, D. Červenkov, M. -C. Chang, P. Chang, V. Chekelian, A. Chen, B. G. Cheon, K. Chilikin, H. E. Cho, K. Cho, S. -J. Cho, S. -K. Choi, Y. Choi, S. Choudhury, D. Cinabro, S. Das, G. De Pietro, R. Dhamija, F. Di Capua, J. Dingfelder, Z. Doležal, T. V. Dong, D. Epifanov, T. Ferber, D. Ferlewicz, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Garmash, A. Giri, P. Goldenzweig, E. Graziani, C. Hadjivasiliou, H. Hayashii, W. -S. Hou, C. -L. Hsu, K. Inami, N. Ipsita, A. Ishikawa, R. Itoh, M. Iwasaki, W. W. Jacobs, E. -J. Jang, S. Jia, Y. Jin, K. K. Joo, H. Kakuno, K. H. Kang, G. Karyan, T. Kawasaki, C. Kiesling, C. H. Kim, D. Y. Kim, K. -H. Kim, Y. -K. Kim, P. Kodyš, T. Konno, A. Korobov, S. Korpar, E. Kovalenko, P. Križan, P. Krokovny, M. Kumar, R. Kumar, K. Kumara, T. Lam, J. S. Lange, S. C. Lee, C. H. Li, J. Li, L. K. Li. 2022-08-09. Measurement of two-photon decay width of $\chi_{c2}(1P)$ in $ \gamma \gamma \rightarrow \chi_{c2}(1P) \rightarrow J/\psi\gamma$ at Belle. https://arxiv.org/abs/2208.04477

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