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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2002, vol. 65, p. -

Study of the ππ mass spectra in the process e+e - → π+π-π0 at √s≃1020 MeV

Achasov M. N., Aulchenko V. M., Beloborodov K. I., Berdyugin A. V., Bogdanchikov A. G., Bozhenok A. V., Bukin A. D., Bukin D. A., Burdin S. V., Dimova T. V., Druzhinin V. P., Golubev V. B., Ivanchenko V. N., Ivanov P. M., Korol A. A., Korostelev M. S., Koshuba S. V., Otboev A. V., Pakhtusova E. V., Perevedentsev E. A., Salnikov A. A., Serednyakov S. I., Shary V. V., Shatunov Yu M., Sidorov V. A., Silagadze Z. K., Vasiljev A. V., Velikzhanin Yu S.

The invariant mass spectra of the π+π- and π±π0 pairs in the process e+e - → π+π-π0 were studied in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region √s≃1020 MeV. These studies were based on about 0.5×106 events. The spectra were analyzed in the framework of the vector meson dominance model. It was found that the experimental data can be described assuming the e+e-→ ρπ →π+π-π0 transition only. An upper limit on the branching ratio of the φ(1020)→π+π -π0 decay through intermediate states different from ρπ was obtained at the 90% confidence level: B(φ? →π+π-π0)<6 × 10 -4. The ρ-meson mass and width which follow from the spectra analysis are mρ=775.0±1.3 MeV, Γρ = 150.4±3.0 MeV. The mass difference of the neutral and charged ρ mesons was found to equal mρ± -mρ0 = -1.3 ± 2.3 MeV. In the π+π- mass spectrum the ρ-ω interference was seen at a two standard deviation level. © 2002 The American Physical Society.