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تسجيل مستخدم جديدSearch for the $B to Y(4260) K, ~Y(4260) to J/psi pi^+pi^-$ decays
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We report the results of a search for the $B to Y(4260) K, ~Y(4260)to J/psipi^+pi^-$ decays. This study is based on a data sample corresponding to an integrated luminosity of 711~fb$^{-1}$, collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We investigate the $J/psipi^+pi^-$ invariant mass distribution in the range 4.0 to 4.6 GeV/$c^2$ using both $B^+ to J/psi pi^+pi^- K^+$ and $B^0 to J/psi pi^+pi^- K^0_S$ 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 $B to Y(4260) K$ decays, respectively, taking into account the systematic uncertainties. These correspond to upper limits on the product of branching fractions, ${cal B}(B^+ to Y(4260) K^+) times {cal B}(Y(4260) to J/psi pi^+ pi^-) <1.4 times 10^{-5}$ and ${cal B}(B^0 to Y(4260) K^0) times {cal B}(Y(4260) to J/psi pi^+ pi^-) <1.7 times 10^{-5}$ at the 90% confidence level.
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