Measurement of B0 ---> D(*)+ D*- branching fractions and B0 ---> D*+(s) D*- polarization with a partial reconstruction technique

We present a study of the decays B0->D_s(*)+D*-, using 20.8 fb-1 of e+e- annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the D_s(*)+ and the soft pion from the D*- decay are reconstructed. We measure the branching fractions BR(B0->D_s+D*-) = (1.03 +/- 0.14 +/- 0.13 +/- 0.26)% and BR(B0->D_s*+D*-) = (1.97 +/- 0.15 +/- 0.30 +/- 0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the D_s+->phi pi+ branching fraction uncertainty. From the B0->D_s*+D*- angular distributions, we measure the fraction of longitudinal polarization Gamma_L/Gamma = (51.9 +/- 5.0 +/- 2.8)%, which is consistent with theoretical predictions based on factorization.Comment: 9 pages, 4 postscript figues, submitted to Physical Review D (Rapid Communications

Measurement of the branching fraction and CP violating asymmetries in neutral B decays to D*+- D-+

We present measurements of the branching fraction and CP-violating asymmetries for neutral B decays to D*+-D-+. The measurement uses a data sample of approximately 88 million Y(4S) --> B Bbar decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We measure the branching fraction to be (8.8 +- 1.0 +- 1.3) x 10^-4 and the time-integrated CP-violating asymmetry between the rates to D*+D- and D*-D+ to be A = -0.03 +- 0.11 +- 0.05. We also measure the time-dependent CP-violating asymmetry parameters to be S-+ = -0.24 +- 0.69 +- 0.12, C-+ = -0.22 +- 0.37 +- 0.10 for B --> D*-D+ and S+- = -0.82 +- 0.75 +- 0.14$, C+- = -0.47 +- 0.40 +- 0.12 for B --> D*+D-. In each case the first error is statistical and the second error is systematic.Comment: 7 pages, 3 figures, published as Phys. Rev. Lett 90 (2003) 22180

Measurement of the CKM matrix element |V(ub)| with B ---> rho e nu decays

We present a measurement of the branching fraction for the rare decays B->rho e nu and extract a value for the magnitude of Vub, one of the smallest elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are given for five different calculations of form factors used to parametrize the hadronic current in semileptonic decays. Using a sample of 55 million BBbar meson pairs recorded with the BABAR detector at the PEP-II e+e- storage ring, we obtain Br(B0->rho- e+ nu)=(3.29 +-0.42 +-0.47 +-0.60) x 10^-4 and |Vub|=(3.64 +-0.22 +-0.25 +0.39-0.56)x10^-3, where the uncertainties are statistical, systematic, and theoretical, respectively.Comment: Submitted to Phys. Rev. Let