Measurement of the B± → ρ±π0 branching fraction and direct CP asymmetry

We present improved measurements of the branching fraction and C P asymmetry for the process B ± → ρ ± π 0 . The data sample corresponding to 211 fb − 1 comprises 232 × 10 6 Υ ( 4 S ) → B ¯¯¯ B decays collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. The yield and C P asymmetry are measured using an extended maximum likelihood fitting method. The branching fraction and C P asymmetry are found to be B ( B ± → ρ ± π 0 ) = [ 10.2 ± 1.4 ( stat ) ± 0.9 ( syst ) ] × 10 − 6 and A C P ( B ± → ρ ± π 0 ) = − 0.01 ± 0.13 ( stat ) ± 0.02 ( syst )