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arXiv · 2608.03417

Evidence of the $e^+ e^-\to f_1(1285)$ reaction with the CMD-3 detector at VEPP-2000

E. P. Solodov·R. R. Akhmetshin·A. N. Amirkhanov·A. V. Anisenkov·V. M. Aulchenko·N. S. Bashtovoy·E. V. Bedarev·D. E. Berkaev·A. E. Bondar·A. V. Bragin·D. E. Chistyakov·V. S. Denisov·E. A. Eminov·D. A. Epifanov·L. B. Epshteyn·A. L. Erofeev·G. V. Fedotovich·L. B. Fomin·A. O. Gorkovenko·A. A. Grebenuk·S. S. Gribanov·D. N. Grigoriev·F. V. Ignatov·V. L. Ivanov·A. S. Kasaev·S. V. Karpov·V. F. Kazanin·I. A. Koop·A. A. Korobov·A. N. Kozyrev·P. P. Krokovny·A. S. Kuzmin·T. A. Kuznetsov·I. B. Logashenko·P. A. Lukin·K. Yu. Mikhailov·I. V. Obraztsov·V. G. Petrochenko·N. A. Petrov·A. S. Popov·S. A. Rastigeev·Yu. A. Rogovsky·A. A. Ruban·A. E. Ryzhenenkov·A. V. Semenov·V. E. Shebalin·D. N. Shemyakin·B. A. Shwartz·D. B. Shwartz·M. V. Timoshenko·V. M. Titov·A. A. Talyshev·S. S. Tolmachev·A. I. Vorobiov·D. S. Zhadan·Yu. V. Yudin
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Abstract

A search for the $e^+ e^-\to f_1(1285)$ reaction is performed with the CMD-3 detector at the VEPP-2000 collider. Data from a scan in the center-of-mass energy range Ec.m.=1.20--1.36 GeV with 109.1 pb$^{-1}$ of the integrated luminosity is used. A dedicated 51.7 pb$^{-1}$ have been collected at the $f_1(1285)$ resonance peak energy Ec.m.=1282 MeV, where $26.5 \pm 7.4$ events have been found in the $e^+ e^-\to\eta\pi^0\pi^0$ reaction. No indication of the signal is observed in the scan data. We interpret the result as 4.5$\sigma$ evidence of the C-even resonance production in the $e^+ e^-\to f_1(1285)\to\eta\pi^0\pi^0$ reaction via the two-photon interaction. The production cross section is found to be $\sigma(e^+ e^-\to f_1) = 0.074 \pm 0.021 \pm 0.010$ nb, and the corresponding branching fraction to the $e^+ e^-$ pair is $B(f_1(1285)\to e^+e^-) = (8.3 \pm 2.3 \pm 1.1)\times 10^{-9}$.

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E. P. Solodov, R. R. Akhmetshin, A. N. Amirkhanov, A. V. Anisenkov, V. M. Aulchenko, N. S. Bashtovoy, E. V. Bedarev, D. E. Berkaev, A. E. Bondar, A. V. Bragin, D. E. Chistyakov, V. S. Denisov, E. A. Eminov, D. A. Epifanov, L. B. Epshteyn, A. L. Erofeev, G. V. Fedotovich, L. B. Fomin, A. O. Gorkovenko, A. A. Grebenuk, S. S. Gribanov, D. N. Grigoriev, F. V. Ignatov, V. L. Ivanov, A. S. Kasaev, S. V. Karpov, V. F. Kazanin, I. A. Koop, A. A. Korobov, A. N. Kozyrev, P. P. Krokovny, A. S. Kuzmin, T. A. Kuznetsov, I. B. Logashenko, P. A. Lukin, K. Yu. Mikhailov, I. V. Obraztsov, V. G. Petrochenko, N. A. Petrov, A. S. Popov, S. A. Rastigeev, Yu. A. Rogovsky, A. A. Ruban, A. E. Ryzhenenkov, A. V. Semenov, V. E. Shebalin, D. N. Shemyakin, B. A. Shwartz, D. B. Shwartz, M. V. Timoshenko, V. M. Titov, A. A. Talyshev, S. S. Tolmachev, A. I. Vorobiov, D. S. Zhadan, Yu. V. Yudin. 2026-08-04. Evidence of the $e^+ e^-\to f_1(1285)$ reaction with the CMD-3 detector at VEPP-2000. https://arxiv.org/abs/2608.03417

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