Measurement of the branching fraction and $CP$ asymmetry for $B\to\bar{D}^{0} \pi$ decays

We measure the branching fractions and CP asymmetries for the decays B0 → D ¯ 0π0 and B+ → D ¯ 0π+ , using a data sample of 772×106 B B ¯ pairs collected at the ϒ ( 4S ) resonance with the Belle detector at the KEKB e+e- collider. The branching fractions obtained and direct CP asymmetries are B ( B0 → D ¯ 0π0 ) = [ 2.70±0.06 ( stat ) ±0.10 ( syst ) ] ×10-4 , B ( B+ → D ¯ 0π+ ) = [ 4.53±0.02 ( stat ) ± 0.15 ( syst ) ] ×10-3 , A CP ( B0 → D ¯ 0π0 ) = [ +0.42±2.05 ( stat ) ±1.22 ( syst ) ] % , and A CP ( B+ → D ¯ 0π+ ) = [ +0.19±0.36 ( stat ) ±0.57 ( syst ) ] % . The measurements of B are the most precise to date and are in good agreement with previous results, as is the measurement of A CP ( B+ → D ¯ 0π+ ) . The measurement of A CP for B0 → D ¯ 0π0 is the first for this mode, and the value is consistent with Standard Model expectations.