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arXiv · 2302.08834

Measurement of the $e^+e^-\to\pi^+\pi^-$ cross section from threshold to 1.2 GeV with the CMD-3 detector

3 Collaboration·F. V. Ignatov·R. R. Akhmetshin·A. N. Amirkhanov·A. V. Anisenkov·V. M. Aulchenko·N. S. Bashtovoy·D. E. Berkaev·A. E. Bondar·A. V. Bragin·S. I. Eidelman·D. A. Epifanov·L. B. Epshteyn·A. L. Erofeev·G. V. Fedotovich·A. O. Gorkovenko·F. J. Grancagnolo·A. A. Grebenuk·S. S. Gribanov·D. N. Grigoriev·V. L. Ivanov·S. V. Karpov·A. S. Kasaev·V. F. Kazanin·B. I. Khazin·A. N. Kirpotin·I. A. Koop·A. A. Korobov·A. N. Kozyrev·E. A. Kozyrev·P. P. Krokovny·A. E. Kuzmenko·A. S. Kuzmin·I. B. Logashenko·P. A. Lukin·A. P. Lysenko·K. Yu. Mikhailov·I. V. Obraztsov·V. S. Okhapkin·A. V. Otboev·E. A. Perevedentsev·Yu. N. Pestov·A. S. Popov·G. P. Razuvaev·Yu. A. Rogovsky·A. A. Ruban·N. M. Ryskulov·A. E. Ryzhenenkov·A. V. Semenov·A. I. Senchenko·P. Yu. Shatunov·Yu. M. Shatunov·V. E. Shebalin·D. N. Shemyakin·B. A. Shwartz·D. B. Shwartz·A. L. Sibidanov·E. P. Solodov·A. A. Talyshev·M. V. Timoshenko·V. M. Titov·S. S. Tolmachev·A. I. Vorobiov·I. M. Zemlyansky·D. S. Zhadan·Yu. M. Zharinov·A. S. Zubakin·Yu. V. Yudin
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Abstract

The cross section of the process $e^+e^-\to\pi^+\pi^-$ has been measured in the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on a full dataset collected below 1 GeV during three data taking seasons, corresponding to an integrated luminosity of about 62 pb$^{-1}$. In the dominant $\rho$-resonance region, a systematic uncertainty of 0.7% has been reached. At energies around $\phi$-resonance the $\pi^+\pi^-$ production cross section was measured for the first time with high beam energy resolution. The forward-backward charge asymmetry in the $\pi^+\pi^-$ production has also been measured. It shows a strong deviation from the theoretical prediction based on the conventional scalar quantum electrodynamics framework, and it is in good agreement with the generalized vector-meson-dominance and dispersive-based predictions. The impact of the presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed.

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3 Collaboration, F. V. Ignatov, R. R. Akhmetshin, A. N. Amirkhanov, A. V. Anisenkov, V. M. Aulchenko, N. S. Bashtovoy, D. E. Berkaev, A. E. Bondar, A. V. Bragin, S. I. Eidelman, D. A. Epifanov, L. B. Epshteyn, A. L. Erofeev, G. V. Fedotovich, A. O. Gorkovenko, F. J. Grancagnolo, A. A. Grebenuk, S. S. Gribanov, D. N. Grigoriev, V. L. Ivanov, S. V. Karpov, A. S. Kasaev, V. F. Kazanin, B. I. Khazin, A. N. Kirpotin, I. A. Koop, A. A. Korobov, A. N. Kozyrev, E. A. Kozyrev, P. P. Krokovny, A. E. Kuzmenko, A. S. Kuzmin, I. B. Logashenko, P. A. Lukin, A. P. Lysenko, K. Yu. Mikhailov, I. V. Obraztsov, V. S. Okhapkin, A. V. Otboev, E. A. Perevedentsev, Yu. N. Pestov, A. S. Popov, G. P. Razuvaev, Yu. A. Rogovsky, A. A. Ruban, N. M. Ryskulov, A. E. Ryzhenenkov, A. V. Semenov, A. I. Senchenko, P. Yu. Shatunov, Yu. M. Shatunov, V. E. Shebalin, D. N. Shemyakin, B. A. Shwartz, D. B. Shwartz, A. L. Sibidanov, E. P. Solodov, A. A. Talyshev, M. V. Timoshenko, V. M. Titov, S. S. Tolmachev, A. I. Vorobiov, I. M. Zemlyansky, D. S. Zhadan, Yu. M. Zharinov, A. S. Zubakin, Yu. V. Yudin. 2023-02-17. Measurement of the $e^+e^-\to\pi^+\pi^-$ cross section from threshold to 1.2 GeV with the CMD-3 detector. https://doi.org/10.1103/physrevd.109.112002

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