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Article

Search for the B →Y(4260)K, Y(4260) →J/ψπ+π- decays

Аушев Т. А., Mizuk R., Pakhlov P., Pakhlova G., Попов В. Е., Углов Т. В.

We report the results of a search for the BY(4260)KY(4260)→J/ψπ+π− decays. This study is based on a data sample corresponding to an integrated luminosity of 711~fb−1 , collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We investigate the J/ψπ+π− invariant mass distribution in the range 4.0 to 4.6 GeV/c2 using both B+→J/ψπ+πK+ and B0→J/ψπ+πK0S decays. We find excesses of events above the background levels, with a significances of 2.1 and 0.9 standard deviations for charged and neutral BY(4260)K decays, respectively, taking into account the systematic uncertainties. These correspond to upper limits on the product of branching fractions, B(B+→Y(4260)K+)×B(Y(4260)→J/ψπ+π−)<1.4×10−5 and B(B0→Y(4260)K0)×B(Y(4260)→J/ψπ+π−)<1.7×10−5 at the 90\% confidence level.