Measurement of the branching fraction of B → DðÞπlν at Belle using hadronic tagging in fully reconstructed events

We report a measurement of the branching fractions of the decays B→D(*)πℓν. The analysis uses 772×106 B¯B pairs produced in e+e−→Υ(4S) data recorded by the Belle experiment at the KEKB asymmetric-energy e+e− collider. The tagging B meson in the decay is fully reconstructed in a hadronic decay mode. On the signal side, we reconstruct the decay B→D(*)πℓν(ℓ=e,μ). The measured branching fractions are B(B+→D−π+ℓ+ν)=[4.55±0.27 (stat.)±0.39 (syst.)]×10−3, B(B0→¯D0π−ℓ+ν)=[4.05±0.36 (stat.)±0.41 (syst.)]×10−3, B(B+→D*−π+ℓ+ν)=[6.03±0.43 (stat.)±0.38 (syst.)]×10−3, and B(B0→¯D*0π−ℓ+ν)=[6.46±0.53 (stat.)±0.52 (syst.)]×10−3. These are in good agreement with the current world-average values.