A Study of Factorization and a Measurement of CP Violation

Abstract

We report on a study of the decay $\bar{B}$0 → D*+ ωπ- with the BABAR detector at the PEP-II B-factory at the Stanford Linear Accelerator Center. Based on a sample of 232 million B0$\bar{B}$0 decays collected between 1999 and 2004, we measure the branching fraction β}($\bar{B}$0 → D*+ ωπ-) = (2.88 ± 0.21(stat.) ± 0.31(syst.)) x 10-3. We study the invariant mass spectrum of the ωπ- system in this decay. This spectrum is in good agreement with expectations based on factorization and the measured spectrum in τ- → ωπ- vτ. We also measure the polarization of the D*+ as a function of the ωπ- mass. In the mass region 1.1 to 1.9 GeV we measure the fraction of longitudinal polarization of the D*+ to be ΓL/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 $\bar{B}$0 → D*+ ρ(1450)-, ρ(1450)- → ωπ-. Furthermore, we present the results on the time-dependent CP asymmetry in neutral B meson decays to the CP eigenstate J/ΨKL. The measurements use a data sample of about 88 million Y(4S) → B$\bar{B}$ decays collected between 1999 and 2002 with the BABAR detector. We study events in which one neutral B meson is fully reconstructed in the J/ΨKL final state and the other B meson is determined to be either a B0 or a $\bar{B}$0 from its decay products. The amplitude of the CP asymmetry, which in the Standard Model is proportional to sin 2β, is derived from the decay-time distributions in such events. We measure sin 2β = 0.723 ± 0.158(stat.) ± 0.086(syst.), which is consistent with Standard Model expectations.