Measurement of ${\eta }_c\left(1S\right)$ , ${\eta }_c\left(2S\right)$ , and nonresonant ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ production via two-photon collisions

Journal Article · Wed Oct 03 00:00:00 EDT 2018 · Physical Review. D.

DOI:https://doi.org/10.1103/PhysRevD.98.072001· OSTI ID:1477581

Xu, Q. N.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Ayad, R.; Babu, V.; Badhrees, I.; Bakich, A. M.; Bansal, V.; Barberio, E.; Behera, P.; Berger, M.; Bhardwaj, V.; Bhuyan, B.; Biswal, J.; Bondar, A. ; Bozek, A.; Bračko, M.; Červenkov, D.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, K.; Choi, S. -K.; Choi, Y.; Cinabro, D.; Cunliffe, S.; Czank, T.; Dash, N.; Di Carlo, S.; Doležal, Z.; Drásal, Z.; Eidelman, S.; Epifanov, D.; Fast, J. E.; Ferber, T.; Fulsom, B. G.; Garg, R.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gelb, M.; Goldenzweig, P.; Guan, Y.; Guido, E.; Haba, J.; Hayasaka, K.; Hayashii, H.; Hedges, M. T.; Hou, W. -S.; Inami, K.; Inguglia, G.; Ishikawa, A.; Itoh, R.; Iwasaki, M.; Iwasaki, Y.; Jaegle, I.; Jeon, H. B.; Jin, Y.; Joo, K. K.; Julius, T.; Kaliyar, A. B.; Kang, K. H.; Karyan, G.; Kawasaki, T.; Kichimi, H.; Kiesling, C.; Kim, D. Y.; Kim, H. J.; Kim, J. B.; Kodyš, P.; Korpar, S.; Kotchetkov, D.; Križan, P.; Kroeger, R.; Krokovny, P.; Kulasiri, R.; Kwon, Y. -J.; Lee, I. S.; Lee, S. C.; Li, L. K.; Li, Y.; Li Gioi, L.; Libby, J.; Liventsev, D.; Lubej, M.; Luo, T.; Masuda, M.; Matsuda, T.; Matvienko, D.; Merola, M.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Moon, H. K.; Mori, T.; Mussa, R.; Nanut, T.; Nath, K. J.; Natkaniec, Z.; Nayak, M.; Nisar, N. K.; Nishida, S.; Okuno, S.; Ono, H.; Onuki, Y.; Pakhlov, P.; Pakhlova, G.; Pal, B.; Park, H.; Paul, S.; Pedlar, T. K.; Pestotnik, R.; Piilonen, L. E.; Popov, V.; Ritter, M.; Rostomyan, A.; Russo, G.; Sakai, Y.; Salehi, M.; Sandilya, S.; Sanuki, T.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Seino, Y.; Senyo, K.; Seon, O.; Sevior, M. E.; Shebalin, V.; Shen, C. P.; Shibata, T. -A.; Shimizu, N.; Shiu, J. -G.; Sokolov, A.; Solovieva, E.; Starič, M.; Strube, J. F.; Sumiyoshi, T.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Uchida, M.; Uehara, S.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Van Hulse, C.; Varner, G.; Vinokurova, A.; Vorobyev, V.; Vossen, A.; Wang, B.; Wang, C. H.; Wang, M. -Z.; Wang, P.; Wang, X. L.; Watanabe, M.; Watanabe, Y.; Widmann, E.; Won, E.; Ye, H.; Yuan, C. Z.; Yusa, Y.; Zakharov, S.; Zhang, C. C.; Zhang, Z. P.; Zhilich, V.; Zhukova, V.; Zhulanov, V.; Zupanc, A.

We report the measurement of $\gamma \gamma \to {\eta }_c\left(1S\right),{\eta }_c\left(2S\right)\to {\eta }^{\text{'}}{\pi }^{+}{\pi }^{-}$ with ${\eta }^{\text{'}}$ decays to $\gamma \rho$ and $\eta {\pi }^{+}{\pi }^{-}$ using $941{\mathrm{fb}}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The ${\eta }_c\left(1S\right)$ mass and width are measured to be $M=\left[2984.6\pm 0.7\right(\mathrm{stat})\pm 2.2(\mathrm{syst})\pm 0.3(\mathrm{model}\left)\right]\mathrm{MeV}/c^2$ and $\mathrm{\Gamma }=\left[30.8_{-2.2}^{+2.3}\right(\mathrm{stat})\pm 2.5(\mathrm{syst})\pm 1.4(\mathrm{model}\left)\right]\mathrm{MeV}$, respectively. First observation of ${\eta }_c\left(2S\right)\to {\eta }^{\text{'}}{\pi }^{+}{\pi }^{-}$ with a significance of $5.5\sigma$ including systematic error is obtained, and the ${\eta }_c\left(2S\right)$ mass is measured to be $M=\left[3635.1\pm 3.7\right(\mathrm{stat})\pm 2.9(\mathrm{syst})\pm 0.4(\mathrm{model}\left)\right]\mathrm{MeV}/c^2$. The products of the two-photon decay width and branching fraction ( $\mathcal{B}$) of decays to ${\eta }^{\text{'}}{\pi }^{+}{\pi }^{-}$ are determined to be ${\mathrm{\Gamma }}_{\gamma \gamma }$ ${\mathrm{\Gamma }}_{\gamma \gamma }\mathcal{B}=[65.4\pm 2.6(\mathrm{stat}\left)\pm 7.8\right(\mathrm{syst}\left)\right]\mathrm{eV}$ for ${\eta }_c\left(1S\right)$ and $\left[{5.6}_{-1.1}^{+1.2}\right(\mathrm{stat})\pm 1.1(\mathrm{syst}\left)\right]\mathrm{eV}$ for ${\eta }_c\left(2S\right)$. The cross sections for $\gamma \gamma \to {\eta }^{\text{'}}{\pi }^{+}{\pi }^{-}$ and ${\eta }^{\text{'}}{f}_2\left(1270\right)$ are measured for the first time.

• Research Organization: Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Univ. of Hawaii, Honolulu, HI (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF)
• Contributing Organization: Belle Collaboration
• Grant/Contract Number: SC0009973; SC0010504
• OSTI ID: 1477581
• Alternate ID(s): OSTI ID: 1593918
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Vol. 98 Journal Issue: 7; ISSN 2470-0010
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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