## Abstract

We report measurements of the charmless semileptonic decays B^{0} → π^{-} / ρ^{-} ℓ^{+} ν and B^{+} → π^{0} / ρ^{0} ℓ^{+} ν, based on a sample of 2.75 × 10^{8}B over(B, ̄) events collected at the Υ{hooked} (4 S) resonance with the Belle detector at the KEKB e^{+} e^{-} asymmetric collider. In this analysis, the accompanying B meson is reconstructed in the semileptonic mode B → D^{(*)} ℓ ν, enabling detection of the signal modes with high purity. We measure the branching fractions B (B^{0} → π^{-} ℓ^{+} ν) = (1.38 ± 0.19 ± 0.14 ± 0.03) × 10^{-4}, B (B^{0} → ρ^{-} ℓ^{+} ν) = (2.17 ± 0.54 ± 0.31 ± 0.08) × 10^{-4}, B (B^{+} → π^{0} ℓ^{+} ν) = (0.77 ± 0.14 ± 0.08 ± 0.00) × 10^{-4} and B (B^{+} → ρ^{0} ℓ^{+} ν) = (1.33 ± 0.23 ± 0.17 ± 0.05) × 10^{-4}, where the errors are statistical, experimental systematic, and systematic due to form factor uncertainties, respectively. For each mode we also present the partial branching fractions in three q^{2} intervals: q^{2} < 8, 8 ≤ q^{2} < 16, and q^{2} ≥ 16 GeV^{2} / c^{2}. From our partial branching fractions for B → π ℓ ν and recent results for the form factor from unquenched Lattice QCD calculations, we obtain values of the CKM matrix element | V_{u b} |.

Original language | English |
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Pages (from-to) | 139-148 |

Number of pages | 10 |

Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |

Volume | 648 |

Issue number | 2-3 |

DOIs | |

Publication status | Published - 2007 May 3 |

## Keywords

- B decay
- Exclusive
- Semileptonic

## ASJC Scopus subject areas

- Nuclear and High Energy Physics

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