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arXiv · 1012.1694

Measurement of B(J/psi->eta_c gamma) 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·O. L. Beloborodova·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·A. I. Milstein·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·D. N. Shatilov·G. E. Pospelov·V. G. Prisekin·A. A. Ruban·V. K. Sandyrev·G. A. Savinov·A. G. Shamov·B. A. Shwartz·E. A. Simonov·S. V. Sinyatkin·Yu. I. Skovpen·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

We present a study of the inclusive photon spectrum from 6.3 million J/psi decays collected with the KEDR detector at the VEPP-4M e+e- collider. We measure the branching fraction of the radiative decay J/psi -> eta_c gamma, eta_c width and mass. Taking into account an asymmetric photon line shape we obtain: M(eta_c) = (2978.1 +- 1.4 +- 2.0) MeV/c^2, Gamma(eta_c) = (43.5 +- 5.4 +- 15.8) MeV, B(J/psi->eta_c gamma) = (2.59 +- 0.16 +- 0.31)%$.

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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, O. L. Beloborodova, 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, A. I. Milstein, 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, D. N. Shatilov, G. E. Pospelov, V. G. Prisekin, A. A. Ruban, V. K. Sandyrev, G. A. Savinov, A. G. Shamov, B. A. Shwartz, E. A. Simonov, S. V. Sinyatkin, Yu. I. Skovpen, 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. 2010-12-08. Measurement of B(J/psi->eta_c gamma) at KEDR. https://doi.org/10.1142/s2010194511000791

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