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Search for the radiative decay $η\to π^0 γγ$ in the SND experiment at VEPP-2M

M. N. Achasov·K. I. Beloborodov·A. V. Berdyugin·A. V. Bozhenok·A. G. Bogdanchikov·D. A. Bukin·S. V. Burdin·T. V. Dimova·A. A. Drozdetsky·V. P. Druzhinin·D. I. Ganyushin·V. B. Golubev·V. N. Ivanchenko·I. A. Koop·A. A. Korol·S. V. Koshuba·A. V. Otboev·E. V. Pakhtusova·A. A. Salnikov·V. V. Shary·S. I. Serednyakov·Yu. M. Shatunov·V. A. Sidorov·Z. K. Silagadze·A. G. Skripkin·A. A. Valishev·A. V. Vasiljev·Yu. S. Velikzhanin
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Abstract

The $η\to π^0 γγ$ decay was investigated by the SND detector at VEPP-2M $e^+e^-$ collider in the reaction $e^+e^-\toϕ\to ηγ$. Here we present the results and some details of this study. We report an upper limit (90% c.l.) $Br(η\to π^0 γγ)<8.4\times 10^{-4}$ as our final result. Our upper limit does not contradict the earlier measurement by GAMS spectrometer. To facilitate future studies a rather detailed review of the problem is also given.

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M. N. Achasov, K. I. Beloborodov, A. V. Berdyugin, A. V. Bozhenok, A. G. Bogdanchikov, D. A. Bukin, S. V. Burdin, T. V. Dimova, A. A. Drozdetsky, V. P. Druzhinin, D. I. Ganyushin, V. B. Golubev, V. N. Ivanchenko, I. A. Koop, A. A. Korol, S. V. Koshuba, A. V. Otboev, E. V. Pakhtusova, A. A. Salnikov, V. V. Shary, S. I. Serednyakov, Yu. M. Shatunov, V. A. Sidorov, Z. K. Silagadze, A. G. Skripkin, A. A. Valishev, A. V. Vasiljev, Yu. S. Velikzhanin. 2001-01-25. Search for the radiative decay $η\to π^0 γγ$ in the SND experiment at VEPP-2M. https://doi.org/10.1016/s0550-3213(01)00040-2

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