Study of the decay ¯B0 → D*+ωπ−

Abstract

We report on a study of the decay ¯¯¯ B 0 → D * + ω π − with the BABAR detector at the PEP-II B -factory at the Stanford Linear Accelerator Center. Based on a sample of 232 × 10 6 B ¯¯¯ B decays, we measure the branching fraction B ( ¯¯¯ B 0 → D * + ω π − ) = ( 2.88 ± 0.21 ( stat . ) ± 0.31 ( syst . ) ) × 10 − 3 . We study the invariant mass spectrum of the ω π − system in this decay. This spectrum is in good agreement with expectations based on factorization and the measured spectrum in τ − → ω π − ν τ . We also measure the polarization of the D * + as a function of the ω π − mass. In the mass region 1.1 to 1.9 GeV we measure the fraction of longitudinal polarization of the D * + to be Γ L / Γ = 0.654 ± 0.042 ( stat . ) ± 0.016 ( syst . ) . This is in agreement with the expectations from heavy-quark effective theory and factorization assuming that the decay proceeds as ¯¯¯ B 0 → D * + ρ ( 1450 ) − , ρ ( 1450 ) − → ω π − .