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arXiv · hep-ex/0109026

Observation of the Decay $B \to K \ell^{+} \ell^{-}$

K. Abe
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Abstract

We report a search for the flavor-changing neutral current decay $B \to K^{(*)} \ell^{+} \ell^{-}$ using a 29.1 fb${}^{-1}$ data sample accumulated at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ storage ring. We observe the decay process $B\to K\ell^+\ell^- (\ell = e, μ)$, for the first time, with a branching fraction of ${\cal B}(B \to K \ell^{+} \ell^{-}) = (0.75^{+0.25}_{-0.21} \pm 0.09) \times 10^{-6}$.

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K. Abe. 2001-10-19. Observation of the Decay $B \to K \ell^{+} \ell^{-}$. https://doi.org/10.1103/physrevlett.88.021801

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