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ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 1998, vol. 434, p. 426-436

Study of dynamics of θ → π+π- π0 decay with CMD-2 detector

Akhmetshin R. R., Aksenov G. A., Anashkin E. V., Arpagaus M., Baibusinov B. O., Banzarov V. S., Barkov L. M., Bondar A. E., Chernyak D. V., Danilov V. V., Dvoretsky A. S., Eidelman S. I., Fedotovich G. V., Gabyshev N. I., Grebeniuk A. A., Grigoriev D. N., Ivanov P. M., Khazin B. I., Koop I. A., Kurdadze L. M., Kuzmin A. S., Logashenko I. B., Lukin P. A., Merzlyakov Yu I., Nesterenko I. N., Okhapkin V. S., Polunin A. A., Ptitzyn V. I., Purlatz T. A., Root N. I., Ruban A. A., Ryskulov N. M., Shamov A. G., Shatunov Yu M., Shwartz B. A., Sidorov V. A., Skrinsky A. N., Smakhtin V. P., Snopkov I. G., Solodov E. P., Stepanov P. Yu, Sukhanov A. I., Titov V. M., Yudin Yu V., Zverev S. G., Brown D. H., Roberts B. L., Thompson J. A., Hughes V. W.

A study of the θ → π+ π- π0 decay mode has been performed using a data sample of about 2.0 million θ decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. The following parameters of the θ-meson have been measured: Br(θ → π+ π- π0) = 0.145 ± 0.009 ± 0.003 and δθ-ω = 162 ± 17°. The analysis of the Dalitz plot showed the dominance of the θ → ρπ intermediate mechanism, the limits for the ratio of the direct amplitude of θ → 3π to that of θ → ρπ are -0.16 < a1 < 0.11 at 90% C.L. The upper limits for the probabilities of the decay modes θ → π+ π- η and direct θ → ργγ have been found for the first time: Br(θ → π+ π- η) < 3 × 10-4 and Br(θ → ργγ) < 5 × 10-4 at 90% C.L. © 1998 Published by Elsevier Science B.V. All rights reserved.