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 measurements of the B→ηKγ branching fractions and upper limits for the B→η′Kγ branching fractions. For B+→ηK+γ we also measure the time-integrated charge asymmetry. The data sample, collected with the BABAR detector at the Stanford Linear Accelerator Center, represents 232×106 produced BB̄ pairs. The results for branching fractions and upper limits at 90% confidence level in units of 10-6 are: B(B0→ηK0γ)=11.3-2.6+2.8±0.6, B(B+→ηK+γ)=10.0±1.3±0.5, B(B0→η′ K0γ)<6.6, B(B+→η′K+γ)<4.2. The charge asymmetry in the decay B+→ηK+γ is Ach=-0.09±0.12±0.01. The first errors are statistical and the second systematic. © 2006 The American Physical Society.

Abstract:

We present measurements of the branching fractions and charge asymmetries of B decays to all D(*)D̄(*) modes. Using 232×106 BB̄ pairs recorded on the Υ(4S) resonance by the BABAR detector at the e+e- asymmetric B factory PEP-II at the Stanford Linear Accelerator Center, we measure the branching fractions B(B0→D*+D*-)=(8.1±0. 6±1.0)×10-4, B(B0→D*±D)=(5.7±0.7±0. 7)×10-4, B(B0→D+D-)=(2.8±0.4±0.5)×10-4, B(B+→D*+D̄*0)=(8.1±1.2±1.2)×10-4, B(B+→D*+D̄0)=(3.6±0.5±0.4)×10-4, B(B+→D+D̄*0)=(6.3±1.4±1.0)×10-4, and B(B+→D+D̄0)=(3.8±0.6±0.5)×10-4, where in each case the first uncertainty is statistical and the second systematic. We also determine the limits B(B0→D*0D̄*0)<0.9×10-4, B(B0→D*0D̄0)<2.9×10-4, and B(B0→D0D̄0)<0. 6×10-4, each at 90% confidence level. All decays above denote either member of a charge-conjugate pair. We also determine the CP-violating charge asymmetries A(B0→D*±D)=0.03±0.10±0.02, A(B+→D*+D̄*0)=-0.15±0.11±0.02, A(B+→D*+D̄0)=-0.06±0.13±0.02, A(B+→D+D̄ *0)=0.13±0.18±0.04, and A(B+→D+D̄0)=-0. 13±0.14±0.02. Additionally, when we combine these results with information from time-dependent CP asymmetries in B0→D(*)+D(*)- decays and world-averaged branching fractions of B decays to Ds(*)D̄(*) modes, we find the Cabibbo-Kobayashi-Maskawa phase γ is favored to lie in the range (0.07-2.77) radians (with a +0 or +π radians ambiguity) at 68% 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.