Measurement of the $e^+e^-\toπ^+π^-π^0$ cross section in the energy region from 0.56 to 1.1 GeV with the SND detector
hep-ex
/ Authors
SND Collaboration, M. N. Achasov, A. E. Alizzi, A. Yu. Barnyakov, K. I. Beloborodov, A. V. Berdyugin, D. E. Berkaev, A. G. Bogdanchikov, A. A. Botov, V. S. Denisov
and 37 more authors
T. V. Dimova, V. P. Druzhinin, R. A. Efremov, E. A. Eminov, L. B. Fomin, L. V. Kardapoltsev, A. A. Kattsin, A. G. Kharlamov, I. A. Koop, A. A. Korol, D. P. Kovrizhin, A. S. Kupich, A. P. Kryukov, N. A. Melnikova, N. Yu. Muchnoi, A. E. Obrazovsky, A. A. Oorzhak, I. V. Ovtin, E. V. Pakhtusova, E. A. Perevedentsev, I. A. Polomoshnov, K. V. Pugachev, Yu. A. Rogovsky
/ Abstract
The precise measurement of the $e^+e^-\toπ^+π^-π^0$ cross section is performed in the center-of-mass energy range $E = 560$--1100 MeV using a data sample of 66 pb$^{-1}$ collected in the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider. The systematic uncertainty of the cross section measurement is 0.9\% at the maximum of the $ω$ resonance and 1.2\% at the maximum of the $φ$ resonance. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the $e^+e^-\toπ^+π^-π^0$ cross section measured by SND from 0.62 to 1.975 GeV is $(45.95\pm0.06\pm 0.46)\times 10^{-10}$. From the fit to the cross section data with the vector meson dominance model, the parameters of the $ω$, $ρ$, and $φ$ resonances are obtained. The obtained values of ${\cal B}(ω\to e^+e^-) {\cal B}(ω\to 3π)$, mass and width of the $ω$ meson, and ${\cal B}(ρ\to 3π)$ have accuracy better than the current world average values.