Aubert, B (reprint author), Phys Particules Lab, F-79471 Annecy Le Vieux, France.
We report on a study of the decay (B) over bar (0)-> D*+omega pi(-) with the BABAR detector at the PEP-II B-factory at the Stanford Linear Accelerator Center. Based on a sample of 232x10(6) B (B) over bar decays, we measure the branching fraction B((B) over bar (0)-> D*+omega pi(-))=(2.88 +/- 0.21(stat.)+/- 0.31(syst.))x10(-3). We study the invariant mass spectrum of the omega pi(-) system in this decay. This spectrum is in good agreement with expectations based on factorization and the measured spectrum in tau(-)->omega pi(-)nu(tau). We also measure the polarization of the D*+ as a function of the omega pi(-) mass. In the mass region 1.1 to 1.9 GeV we measure the fraction of longitudinal polarization of the D*+ to be Gamma(L)/Gamma=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) over bar (0)-> D*+rho(1450)(-), rho(1450)(-)->omega pi(-).