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arXiv · 1406.7644

Measurement of $J/\psi\to\gamma\eta_{\rm c}$ decay rate and $\eta_{\rm c}$ parameters at KEDR

V. V. Anashin·V. M. Aulchenko·E. M. Baldin·A. K. Barladyan·A. Yu. Barnyakov·M. Yu. Barnyakov·S. E. Baru·I. Yu. Basok·I. V. Bedny·A. E. Blinov·V. E. Blinov·A. V. Bobrov·V. S. Bobrovnikov·A. V. Bogomyagkov·A. E. Bondar·A. R. Buzykaev·S. I. Eidelman·Yu. M. Glukhovchenko·V. V. Gulevich·D. V. Gusev·S. E. Karnaev·G. V. Karpov·S. V. Karpov·T. A. Kharlamova·V. A. Kiselev·S. A. Kononov·K. Yu. Kotov·E. A. Kravchenko·V. F. Kulikov·G. Ya. Kurkin·E. A. Kuper·E. B. Levichev·D. A. Maksimov·V. M. Malyshev·A. L. Maslennikov·A. S. Medvedko·O. I. Meshkov·S. I. Mishnev·I. I. Morozov·N. Yu. Muchnoi·V. V. Neufeld·S. A. Nikitin·I. B. Nikolaev·I. N. Okunev·A. P. Onuchin·S. B. Oreshkin·I. O. Orlov·A. A. Osipov·S. V. Peleganchuk·S. G. Pivovarov·P. A. Piminov·V. V. Petrov·A. O. Poluektov·G. E. Pospelov·V. G. Prisekin·O. L. Rezanova·A. A. Ruban·V. K. Sandyrev·G. A. Savinov·A. G. Shamov·D. N. Shatilov·B. A. Shwartz·E. A. Simonov·S. V. Sinyatkin·A. N. Skrinsky·V. V. Smaluk·A. V. Sokolov·A. M. Sukharev·E. V. Starostina·A. A. Talyshev·V. A. Tayursky·V. I. Telnov·Yu. A. Tikhonov·K. Yu. Todyshev·G. M. Tumaikin·Yu. V. Usov·A. I. Vorobiov·A. N. Yushkov·V. N. Zhilich·V. V. Zhulanov·A. N. Zhuravlev
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Abstract

Using the inclusive photon spectrum based on a data sample collected at the $J/\psi$ peak with the KEDR detector at the VEPP-4M $e^+e^-$ collider, we measured the rate of the radiative decay $J/\psi\to\gamma\eta_{\rm c}$ as well as $\eta_{\rm c}$ mass and width. Taking into account an asymmetric photon lineshape we obtained $\Gamma^0_{\gamma\eta_{\rm c}}=2.98\pm0.18 \phantom{|}^{+0.15}_{-0.33}$ keV, $M_{\eta_{\rm c}} = 2983.5 \pm 1.4 \phantom{|}^{+1.6}_{-3.6}$ MeV/$c^2$, $\Gamma_{\eta_{\rm c}} = 27.2 \pm 3.1 \phantom{|}^{+5.4}_{-2.6}$ MeV.

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V. V. Anashin, V. M. Aulchenko, E. M. Baldin, A. K. Barladyan, A. Yu. Barnyakov, M. Yu. Barnyakov, S. E. Baru, I. Yu. Basok, I. V. Bedny, A. E. Blinov, V. E. Blinov, A. V. Bobrov, V. S. Bobrovnikov, A. V. Bogomyagkov, A. E. Bondar, A. R. Buzykaev, S. I. Eidelman, Yu. M. Glukhovchenko, V. V. Gulevich, D. V. Gusev, S. E. Karnaev, G. V. Karpov, S. V. Karpov, T. A. Kharlamova, V. A. Kiselev, S. A. Kononov, K. Yu. Kotov, E. A. Kravchenko, V. F. Kulikov, G. Ya. Kurkin, E. A. Kuper, E. B. Levichev, D. A. Maksimov, V. M. Malyshev, A. L. Maslennikov, A. S. Medvedko, O. I. Meshkov, S. I. Mishnev, I. I. Morozov, N. Yu. Muchnoi, V. V. Neufeld, S. A. Nikitin, I. B. Nikolaev, I. N. Okunev, A. P. Onuchin, S. B. Oreshkin, I. O. Orlov, A. A. Osipov, S. V. Peleganchuk, S. G. Pivovarov, P. A. Piminov, V. V. Petrov, A. O. Poluektov, G. E. Pospelov, V. G. Prisekin, O. L. Rezanova, A. A. Ruban, V. K. Sandyrev, G. A. Savinov, A. G. Shamov, D. N. Shatilov, B. A. Shwartz, E. A. Simonov, S. V. Sinyatkin, A. N. Skrinsky, V. V. Smaluk, A. V. Sokolov, A. M. Sukharev, E. V. Starostina, A. A. Talyshev, V. A. Tayursky, V. I. Telnov, Yu. A. Tikhonov, K. Yu. Todyshev, G. M. Tumaikin, Yu. V. Usov, A. I. Vorobiov, A. N. Yushkov, V. N. Zhilich, V. V. Zhulanov, A. N. Zhuravlev. 2014-06-30. Measurement of $J/\psi\to\gamma\eta_{\rm c}$ decay rate and $\eta_{\rm c}$ parameters at KEDR. https://doi.org/10.1016/j.physletb.2014.09.064

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