Measurement of the branching fraction of <math><mi>B</mi><mo>→</mo><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><mi>π</mi><mo>ℓ</mo><mi>ν</mi></math> 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&#215;106 BB&#175; 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&#177;0.27 (stat.)&#177;0.39 (syst.)]&#215;10−3, B(B0→D&#175;0π−ℓ+ν)=[4.05&#177;0.36 (stat.)&#177;0.41 (syst.)]&#215;10−3, B(B+→D*−π+ℓ+ν)=[6.03&#177;0.43 (stat.)&#177;0.38 (syst.)]&#215;10−3, and B(B0→D&#175;*0π−ℓ+ν)=[6.46&#177;0.53 (stat.)&#177;0.52 (syst.)]&#215;10−3. These are in good agreement with the current world-average values.