Branching ratio and mass spectrum of the decay ϒ′ → ϒπ+π−
1984; Elsevier BV; Volume: 134; Issue: 1-2 Linguagem: Inglês
10.1016/0370-2693(84)91002-5
ISSN1873-2445
AutoresH. Albrecht, G. Drews, H. Hasemann, A. Philipp, W. Schmidt‐Parzefall, H. Schröder, H.D. Schulz, F. Selonke, R. Wurth, A. Drescher, B. Gräwe, W. Hofmann, A. Markees, U. Matthiesen, J. Spengler, D. Wegener, R. Heller, K. R. Schubert, J. Stiewe, R. Waldi, S. Weseler, K. W. Edwards, W.R. Frisken, C. Fukunaga, M. Goddard, P. Kim, R. S. Orr, P. M. Patel, J.D. Prentice, H. Seywerd, T.-S. Yoon, R. Ammar, D. Coppage, R. Davis, N. Kwak, P. Böckmann, L. Jönsson, Y. Oku, A. Arefiev, M. Danilov, V. Lubimov, V. Matveev, V. Nagovitsin, Yu. A. Semënov, V. Shevchenco, V. Soloshenko, V. Sopov, V. Tchernyshev, I. Tichomirov, V. Tchistilin, Yu. Zaitsev, R. Childers, C.W. Darden, H. Gennow,
Tópico(s)Dark Matter and Cosmic Phenomena
ResumoThe reaction e+e− → ϒ′ → ϒπ+π−, with ϒ → anything, has been measured using the ARGUS detector at DORIS . We obtain a mass difference M(ϒ′) − M(ϒ) = (562 ± 3) MeV and a decay branching ratio BR(ϒ′→ϒπ+π−)=(17.9±0.9±2.1)%. The invariant mass spectrum of the π+π− system differs from phase space, but is well described by a matrix element of the form (Mππ2−λMπ2) with λ=2.6±0.5. We also report preliminary results on the exclusive decay ϒ′ → ϒπ+π−, with ϒ → e+e−, and obtain BR(ϒ → e+e−) = (2.8 ± 0.4 ± 04±0.3)%.
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