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Published June 16, 2006 | Published
Journal Article Open

Observation of Υ(4S) Decays to π^+π^-Υ(1S) and π^+π^-Υ(2S)


We present the first measurement of Υ(4S) decays to π^+π^-Υ(1S) and π^+π^-Υ(2S) based on a sample of 230×10^6Υ(4S) mesons collected with the BABAR detector. We measure the product branching fractions B(Υ(4S)→π^+π^-Υ(1S))×B(Υ(1S)→μ^+μ^-)=(2.23±0.25_(stat)±0.27_(syst))×10^(-6) and B(Υ(4S)→π^+π^-Υ(2S))×B(Υ(2S)→μ^+μ^-)=(1.69±0.26_(stat)±0.20_(syst))×10^(-6), from which we derive the partial widths Γ(Υ(4S)→π^+π^-Υ(1S))=(1.8±0.4)  keV and Γ(Υ(4S)→π^+π^-Υ(2S))=(2.7±0.8)  keV.

Additional Information

© 2006 The American Physical Society. Received 14 April 2006; published 13 June 2006. We are grateful for the excellent luminosity and machine conditions provided by our PEP-II colleagues, and for the substantial dedicated effort from the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and kind hospitality. This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from CONACyT (Mexico), Marie Curie EIF (European Union), the A. P. Sloan Foundation, the Research Corporation, and the Alexander von Humboldt Foundation

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