Measurement of the Branching Fraction of B→D(*)πℓν at Belle Using Hadronic Tagging in Fully Reconstructed Events

We report a measurement of the branching fraction of the decay B -> D-(*()) pi l nu. The analysis uses 772X106 B (B) over bar pairs produced in e(+)e(-) -> Upsilon (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-(*()) pi l nu (l=e,mu). The measured branching fractions are B(B+ -> D- (pi)+l(+) nu) = [4.55 +/- 0.27 (stat.) +/- 0.39 (syst.)]X10-3, B(B0?D (_) 0p-l+?) = [4.05 +/- 0.36 (stat.) +/- 0.41 (syst.)]X10(-3), B (B) over bar (D) over bar *0 pi(-)l(+) nu) = [6.03 +/- 0.43 (stat.) +/- 0.38 (syst.)]X10(-3), and B (B) over bar (D) over bar *0 pi(-)l(+) nu) = [6.46 +/- 0.53 (stat.) +/- 0.52 (syst.)10]X-3. These are in good agreement with the current world average values.