We report a measurement of the branching fractions of B̄→D* *ℓ-ν̄ℓ decays based on 417fb-1 of data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e+e- storage rings. Events are selected by fully reconstructing one of the B mesons in a hadronic decay mode. A fit to the invariant mass differences m(D(*)π)- m(D(*)) is performed to extract the signal yields of the different D** states. We observe the B̄→D**ℓ- ν̄ℓ decay modes corresponding to the four D** states predicted by heavy quark symmetry with a significance greater than 5 standard deviations including systematic uncertainties. © 2008 The American Physical Society.

We present a study of resonances in exclusive decays of B mesons to D̄(*)D(*)K. We report the observation of the decays B→D̄(*)Ds1+(2536) where the Ds1+(2536) is reconstructed in the D*0K+ and D*+KS0 decay channels. We report also the observation of the decays B→ψ(3770)K where the ψ(3770) decays to D̄0D0 and D-D+. In addition, we present the observation of an enhancement for the D̄*0D0 invariant mass in the decays B→D̄*0D0K, at a mass of (3875.1-0.5+0.7±0.5)MeV/c2 with a width of (3.0-1.4+1.9±0. 9)MeV (the first errors are statistical and the second are systematic). Branching fractions and spin studies are shown for the three resonances. The results are based on 347fb-1 of data collected with the BABAR detector at the PEP-II B factory. © 2008 The American Physical Society.

We present measurements of the branching fraction and fraction of longitudinal polarization for the decay B+→K̄*0K*+ with a sample of (467±5)×106 BB̄ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. We obtain the branching fraction B(B+→K̄ *0K*+)=(1.2±0.5±0.1)×10-6 with a significance of 3.7 standard deviations including systematic uncertainties. We measure the fraction of longitudinal polarization fL=0.75-0.26+0.16±0.03. The first error quoted is statistical and the second is systematic. © 2009 The American Physical Society.

We present updated measurements of time-dependent CP asymmetries in fully reconstructed neutral B decays containing a charmonium meson. The measurements reported here use a data sample of (465±5)×106 Υ(4S) →BB̄ decays collected with the BABAR detector at the PEP-II asymmetric energy e+e- storage rings operating at the SLAC National Accelerator Laboratory. The time-dependent CP asymmetry parameters measured from JψKS0, JψKL0, ψ(2S)KS0, ηcKS0, χc1KS0, and J/ψK*(892)0 decays are: Cf=0.024±0.020(stat)±0.016(syst) and -ηfSf=0. 687±0.028(stat)±0.012(syst). © 2009 The American Physical Society.

We have searched for D0-D̄0 mixing in D*+→π+D0 decays with D0→K(*)eν in a sample of e+e-→cc̄ events produced near 10.58 GeV. The charge of the slow pion from charged D* decay tags the charm flavor at production, and it is required to be consistent with the flavor of a fully reconstructed second charm decay in the same event. We observe 3 mixed candidates compared to 2.85 background events expected from simulation. We ascribe a 50% systematic uncertainty to this expected background rate. We find a central value for the mixing rate of 0.4×10-4. Using a frequentist method, we set corresponding 68% and 90% confidence intervals at (-5.6,7.4)×10-4 and (-13,12)×10-4, respectively. © 2007 The American Physical Society.

We observe the decays Ds1*(2710)+→D*K and DsJ*(2860)+→D*K and measure their branching fractions relative to the DK final state. We also observe, in the D*K mass spectrum, a new broad structure at a mass of (3044±8stat(+30-5)syst)MeV/c2 having a width Γ=(239±35stat(+46-42)syst)MeV. To obtain this result we use 470fb-1 of data recorded by the BABAR detector at the PEP-II asymmetric-energy e+e- storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV. © 2009 The American Physical Society.

We present a measurement of the branching fraction and photon-energy spectrum for the decay B→Xsγ using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210fb-1, from which approximately 680000 BB̄ events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high-energy photon is identified. We measure B(B→Xsγ)=(3. 66±0.85stat±0.60syst)×10-4 for photon energies Eγ above 1.9GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters mb and μπ2. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented. © 2008 The American Physical Society.

We determine the relative branching fractions of semileptonic B decays to charmed final states. The measurement is performed on the recoil from a fully reconstructed B meson in a sample of 362×106 BB̄ pairs collected at the Υ(4S) resonance with the BABAR detector. A simultaneous fit to a set of discriminating variables is performed on a sample of B̄→DX-ν̄ decays to determine the contributions from the different channels. We measure Γ(B-→D-ν̄)/Γ(B-→DX-ν̄)=0.227±0. 014±0.016, Γ(B-→D*-ν̄)/Γ(B-→DX- ν̄)=0.582±0.018±0.030, and Γ(B-→D **-ν̄)/Γ(B-→DX-ν̄)=0.191±0. 013±0.019 for the charged B sample, and Γ(B0̄→D- ν̄)/Γ(B0̄→DX-ν̄)=0.215±0.016±0. 013, Γ(B0̄→D*-ν̄)/Γ(B0̄→DX- ν̄)=0.537±0.031±0.036, and Γ(B0̄→ D**-ν̄)/Γ(B0̄→DX-ν̄)=0.248±0. 032±0.030 for the neutral B sample, where uncertainties are statistical and systematic, respectively. © 2007 The American Physical Society.

We present a search for the radiative leptonic decay B+→≤+ v≤ γ, where ≤=e, μ, using a data sample of 465×106 BB̄ pairs collected by the BABAR experiment. In this analysis, we fully reconstruct the hadronic decay of one of the B mesons in Υ(4S)→B+B- decays, then search for evidence of B+→≤+ν≤γ in the rest of the event. We observe no significant evidence of signal decays and report model-independent branching fraction upper limits of B(B+→e+νeγ)<17×10-6, B(B+→μ+νμγ)<24×10-6, and B(B+→e+νeγ) <15.6×10-6 (≤=e or μ), all at the 90% confidence level. © 2009 The American Physical Society.

We present an updated measurement of the CP-odd fraction and the time-dependent CP asymmetries in the decay B0→D*+D*- using (383±4)×106BB̄ pairs collected with the BABAR detector. We determine the CP-odd fraction to be 0.143±0.034(stat)±0.008(syst). The time-dependent CP asymmetry parameters are determined to be C+=-0.05±0.14(stat)±0.02(syst) and S+=-0.72±0.19(stat) ±0.05(syst). The nonzero value of the measured S+ indicates the evidence of CP violation at the 3.7σ confidence level. © 2007 The American Physical Society.