Journal article

Measurement of the branching fraction for the decay Υ(4S) →Υ(1S)π+π-

Sokolov, A.; Shapkin, M.; Aihara, H.; Arinstein, K.; Aushev, T.; Bakich, A.M.; Barberio, E.; Bay, A.; Belous, K.; Bhardwaj, V.

We study transitions between Υ states with the emission of charged pions using 604.6fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured product branching fraction is B(Υ(4S)→Υ(1S)π+π-)×B(Υ(1S)→μ+μ-)=(2. 11±0.30(stat)±0.14(sys))×10-6 and the partial decay width is Γ(Υ(4S)→Υ(1S)π+π-)=(1.75±0.25(stat)±0. 24(sys))keV. © 2009 The American Physical Society.


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