Malcolm John

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.

Abstract:

We report a study of the processes e+e-→ηγ and e+e-→η′γ at a center-of-mass energy of 10.58 GeV, using a 232fb-1 data sample collected with the BABAR detector at the PEP-II collider at SLAC. We observe 20-5+6ηγ and 50-7+8η′γ events over small backgrounds, and measure the cross sections σ(e+e- →ηγ)=4.5-1.1+1.2±0.3fb and σ(e+e- →η′γ)=5.4±0.8±0.3fb. The corresponding transition form factors at q2=112GeV2 are q2|Fη(q2)|=0.229±0. 030±0.008GeV, and q2|Fη′(q2)|=0.251±0.019±0. 008GeV, respectively. © 2006 The American Physical Society.

Abstract:

We present updated results on time-dependent CP asymmetries in fully reconstructed B0→D(*)±π and B0→D±ρ decays in approximately 232×106 Υ(4S)→BB̄ events collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. From a time-dependent maximum-likelihood fit we obtain for the parameters related to the CP violation angle 2β+γ: aDπ=-0.010±0.023±0.007, clepDπ=-0.033±0.042±0.012, aD*π=-0.040±0. 023±0.010, clepD*π=0.049±0.042±0.015,aDρ=-0. 024±0.031±0.009, clepDρ=-0.098±0.055±0.018, where the first error is statistical and the second is systematic. Using other measurements and theoretical assumptions, we interpret the results in terms of the angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle and find |sin (2β+γ)|>0.64(0.40) at 68% (90%) confidence level. © 2006 The American Physical Society.

Abstract:

We present measurements of CP-violating asymmetries and branching fractions for the decays B+→ωπ+, B+→ωK+, and B0→ωK0. The data sample corresponds to 232×106 BB̄ pairs produced by e+e- annihilation at the Υ(4S) resonance. For the decay B0→ωKS0, we measure the time-dependent CP-violation parameters S=0.51-0.39+0.35±0.02, and C=-0.55-0.26+0.28±0.03. We also measure the branching fractions, in units of 10-6, B(B+→ωπ+)=6.1±0.7±0.4, B(B+→ωK+)=6.1±0.6±0.4, and B(B0→ωK0)=6. 2±1.0±0.4, and charge asymmetries Ach(B+→ωπ+)=-0. 01±0.10±0.01 and Ach(B+→ωK+)=0.05±0.09±0. 01. © 2006 The American Physical Society.