Malcolm John

Abstract:

We present a study of the decays B̄0→D(*)0K̄(*)0 using a sample of 226×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We report evidence for the decay of B0 and B̄0 mesons to the D*0KS0 final state with an average branching fraction B(B∼0→D*0K∼0) ≡(B(B̄0→D*0K̄0)+B(B0→D*0K0))/2=(3. 6±1.2±0.3)×10-5. Similarly, we measure B(B∼0→ D0K∼0)≡(B(B̄0→D0K̄0)+B(B0→D0K0))/2=(5.3±0. 7±0.3)×10-5 for the D0KS0 final state. We measure B(B̄0→D0K̄*0)=(4.0±0.7±0.3)×10-5 and set a 90% confidence level upper limit B(B̄0→D̄0K̄*0) <1.1×10-5. We determine the upper limit for the decay amplitude ratio |A(B̄0→D̄0K̄*0)/A(B̄0→D0K̄*0)| to be less than 0.4 at the 90% confidence level. © 2006 The American Physical Society.

Abstract:

We present a simultaneous measurement of the B̄0 lifetime τB0 and B0B̄0 oscillation frequency Δmd. We use a sample of about 50000 partially reconstructed B̄0→D*+ℓ-ν̄ℓ decays identified with the BABAR detector at the PEP-II e+e- storage ring at SLAC. The flavor of the other B meson in the event is determined from the charge of another high-momentum lepton. The results are τB0=(1.504±0.013(stat)- 0.013+0.018(syst))ps, Δmd=(0.511±0.007(stat)-0.006+0.007(syst))ps- 1. © 2006 The American Physical Society.

Abstract:

We report a measurement of the B branching fraction based on 211fb-1 of data collected with the BABAR detector. We use samples of B0 and B+ mesons tagged by a second B meson reconstructed in a semileptonic or hadronic decay and combine the results assuming isospin symmetry to obtain B(B0-â., "+Î=(1.33±0.17stat±0.11syst)Ã-10-4. We determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| by combining the partial branching fractions measured in ranges of the momentum transfer squared and theoretical calculations of the form factor. Using a recent lattice QCD calculation, we find |Vub|=(4.5±0. 5stat±0.3syst+0.7-0.5FF)Ã-10-3, where the last error is due to the normalization of the form factor. © 2006 The American Physical Society.

Abstract:

We present measurements of branching fractions of B0 decays to multibody final states containing protons, based on 232×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We measure the branching fractions B(B0→D̄0pp̄)=(1. 13±0.06±0.08)×10-4, B(B0→D̄*0pp̄)=(1. 01±0.10±0.09)×10-4, B(B0→D-pp̄π+)=(3. 38±0.14±0.29)×10-4, and B(B0→D*-pp̄π+)= (4.81±0.22±0.44)×10-4 where the first error is statistical and the second systematic. We present a search for the charmed pentaquark state, Θc(3100) observed by H1 and put limits on the branching fraction B(B0→Θcp̄π+)×B(Θc→D*-p) <14×10-6 and B(B0→Θcp̄π+)×B(Θc→D-p) <9×10-6. Upon investigation of the decay structure of the above four B0 decay modes, we see an enhancement at low pp̄ mass and deviations from phase-space in the D̄p̄ and D̄p invariant mass spectra. © 2006 The American Physical Society.

Abstract:

We measure the dependence of B̄0→D*+e-ν̄e on the decay angles and momentum transfer. The data sample consists of ∼86×106 BB̄-pairs accumulated on the Υ(4S) resonance by the BABAR detector at the asymmetric e+e- collider PEP-II. We specify the three form factors by two ratios R1 and R2, and by a single parameter ρ2 characterizing the polynomial representing hA1, the function which describes the momentum-transfer dependence of the form factor A1. We determine R1, R2, and ρ2 using an unbinned maximum likelihood fit to the full decay distribution. The results are R1=1.396±0.060±0.035±0.027, R2=0.885±0.040±0.022±0.013, and ρ2=1.145±0. 059±0.030±0.035. The stated uncertainties are the statistical from the data, statistical from the size of the Monte Carlo sample and the systematic uncertainty, respectively. In addition, based on this measurement, we give an updated value for the CKM matrix element |Vcb|. © 2006 The American Physical Society.