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First Simultaneous Determination of Inclusive and Exclusive |Vub|
The first simultaneous determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element Vub using inclusive and exclusive decays is performed with the full Belle data set at the Υ(4S) resonance, corresponding to an integrated luminosity of 711 fb−1. We analyze collision events in which one B meson is fully reconstructed in hadronic modes. This allows for the reconstruction of the hadronic Xu system of the semileptonic b→uℓν¯ℓ decay. We separate exclusive B→πℓν¯ℓ decays from other inclusive B→Xuℓν¯ℓ and backgrounds with a two-dimensional fit, that utilizes the number of charged pions in the Xu system and the four-momentum transfer q2 between the B and Xu system. Combining our measurement with information from lattice QCD and QCD calculations of the inclusive partial rate as well as external experimental information on the shape of the B→πℓν¯ℓ form factor, we determine ∣∣Vexcl.ub∣∣=(3.78±0.23±0.16±0.14)×10−3 and ∣∣Vincl.ub∣∣=(3.88±0.20±0.31±0.09)×10−3, respectively, with the uncertainties being the statistical error, systematic errors, and theory errors. The ratio of ∣∣Vexcl.ub∣∣/∣∣Vincl.ub∣∣=0.97±0.12 is compatible with unity.