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arXiv · hep-ex/9807031

First Observation of $Υ(1S)\to γππ$

A. Anastassov
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Abstract

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance collected with the CLEO-II detector operating at CESR. We present the first observation of the radiative decays Upsilon(1S)->gamma pi+pi- and Upsilon(1S)->gamma pi0pi0. For the dipion mass regime m(pipi)>1.0 GeV, we obtain Br(Upsilon(1S)->gamma pi+pi-=(6.3+/-1.2+/-1.3) x 10^(-5), and Br(Upsilon(1S)->gamma pi0pi0=(1.7+/-0.6+/-0.3) x 10^(-5). The observed gamma pipi events are consistent with the hypothesis Upsilon(1S)->gamma f2(1270).

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A. Anastassov. 1998-07-30. First Observation of $Υ(1S)\to γππ$. https://doi.org/10.1103/physrevlett.82.286

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