Measurements of branching fractions and q2 distributions for Bπν and Bρν decays with BD()ν decay tagging

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Abstract

We report measurements of the charmless semileptonic decays B0π/ρ+ν and B+π0/ρ0+ν, based on a sample of 2.75×108 BB¯ events collected at the ϒ(4S) 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 BD()ν, enabling detection of the signal modes with high purity. We measure the branching fractions B(B0π+ν)=(1.38±0.19±0.14±0.03)×10−4, B(B0ρ+ν)=(2.17±0.54±0.31±0.08)×10−4, B(B+π0+ν)=(0.77±0.14±0.08±0.00)×10−4 and B(B+ρ0+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 q2 intervals: q2<8, 8q2<16, and q216GeV2/c2. From our partial branching fractions for Bπν and recent results for the form factor from unquenched Lattice QCD calculations, we obtain values of the CKM matrix element |Vub|.

PACS

12.15.Hh
12.38.Gc
13.25.Hw

Keywords

Semileptonic
B decay
Exclusive

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