Measurement of the e+e− → π+π− process cross section with the SND detector at the VEPP-2000 collider in the energy region 0.525 < $$ \sqrt{s} $$ < 0.883 GeV

• Published in: The journal of high energy physics 2021-01, Vol.2021 (1), Article 113
• Main Authors: Achasov, M. N., Baykov, A. A., Barnyakov, A. Yu, Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Lysenko, A. P., Martin, K. A., Melnikova, N. A., Muchnoi, N. Yu, Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Savchenko, Y. S., Serednyakov, S. I., Silagadze, Z. K., Shatunov, P. Yu, Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., Zemlyansky, I. M., Zhabin, V. N.
• Format: Article
• Language: English
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP01(2021)113

The cross section of the process e + e − → π + π − has been measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2000 e + e − collider VEPP-2000 in the energy region 525 < $$ \sqrt{s} $$ s < 883 MeV. The measurement is based on data with an integrated luminosity of about 4.6 pb − 1 . The systematic uncertainty of the cross section determination is 0.8% at $$ \sqrt{s} $$ s > 0 . 600 GeV. The ρ meson parameters are obtained as m ρ = 775 . 3 ± 0 . 5 ± 0 . 6 MeV, Γ ρ = 145 . 6 ± 0 . 6 ± 0 . 8 MeV, B ρ → e + e− × B ρ → π + π− = (4 . 89 ± 0 . 02 ± 0 . 04) × 10 − 5 , and the parameters of the e + e − → ω → π + π − process, suppressed by G -parity, as B ω → e + e− × B ω → π + π− = (1 . 32 ± 0 . 06 ± 0 . 02) × 10 − 6 and and ϕ ρω = 110 . 7 ± 1 . 5 ± 1 . 0 degrees.