Malcolm John

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 the branching fractions for the Cabbibo suppressed decays D+→π+π0 and D+→K+π0 based on a data sample corresponding to an integrated luminosity of 124.3fb-1. The data were taken with the BABAR detector at the PEP-II B Factory operating on and near the Υ(4S) resonance. We find B(D+→π+π0)=(1.25±0.10±0. 09±0.04)×10-3 and B(D+→K+π0)=(2.52±0.47±0. 25±0.08)×10-4, where the first uncertainty is statistical, the second systematic and the last error is due to the uncertainties in the absolute branching fraction scale for D+ mesons. This represents the first observation of the doubly Cabibbo-suppressed D+→K+π0 decay mode and a new measurement of the D+→π+π0 branching fraction. © 2006 The American Physical Society.

Abstract:

The photon spectrum in B→Xsγ decay, where Xs is any strange hadronic state, is studied using a data sample of 88.5×106 e+e-→Υ(4S)→BB̄ decays collected by the BABAR experiment at the Stanford Linear Accelerator Center. The partial branching fraction, ΔB(B→Xsγ)=(3.67±0.29(stat)±0.34(syst)±0. 29(model))×10-4, the first moment Eγ=2.288±0.025±0. 017±0.015GeV, and the second moment Eγ2=0.0328±0. 0040±0.0023±0.0036GeV2 are measured for the photon energy range 1.9GeV1.6GeV. In addition, the direct CP asymmetry ACP(B→Xs+dγ) is measured to be -0.110±0.115(stat) ±0.017(syst). © 2006 The American Physical Society.

Abstract:

We present a measurement of the inclusive electron spectrum in B→Xueν decays near the kinematic limit for B→Xceν transitions, using a sample of 88×106 BB̄ pairs recorded by the BABAR detector at the Υ(4S) resonance. Partial branching fraction measurements are performed in five overlapping intervals of the electron momentum; for the interval of 2.0-2.6GeV/c we obtain ΔB(B→Xueν)=(0.572±0. 041stat±0.065syst)×10-3. Combining this result with shape function parameters extracted from BABAR measurements of moments of the inclusive photon spectrum in B→Xsγ decays and moments of the hadron-mass and lepton-energy spectra in B→Xcℓν decays we determine |Vub|=(4.44±0.25exp-0.38SF+0.42±0.22theory)×10-3. Here the first error represents the combined statistical and systematic experimental uncertainties of the partial branching fraction measurement, the second error refers to the uncertainty of the determination of the shape function parameters, and the third error is due to theoretical uncertainties in the QCD calculations. © 2006 The American Physical Society.

Abstract:

A measurement of the spin of the Ω- hyperon produced through the exclusive process Ξc0→Ω-K+ is presented using a total integrated luminosity of 116fb-1 recorded with the BABAR detector at the e+e- asymmetric-energy B factory at SLAC. Under the assumption that the Ξc0 has spin 1/2, the angular distribution of the Λ from Ω-→ΛK- decay is inconsistent with all half-integer Ω- spin values other than 3/2. Lower statistics data for the process Ωc0→Ω-π+ from a 230fb-1 sample are also found to be consistent with Ω- spin 3/2. If the Ξc0 spin were 3/2, an Ω- spin of 5/2 could not be excluded. © 2006 The American Physical Society.