Malcolm John

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.

Abstract:

We report searches for B-meson decays to the charmless final states ρK* and f0(980)K* with a sample of 232×106 BB̄ pairs collected with the BABAR detector at the PEP-II e+e- collider. We measure in units of 10-6 the following branching fractions, where the first error quoted is statistical and the second systematic, or upper limits are given at the 90% confidence level: B(B+→ρ0K*+)<6.1, B(B+→ρ+K*0)= 9.6±1.7±1.5, B(B0→ρ-K*+)<12.0, B(B0→ρ0K*0)=5.6±0.9±1.3, B(B+→f0(980) K*+)=5.2±1.2±0.5, and B(B0→f0(980)K*0)<4.3. For the significant modes, we also measure the fraction of longitudinal polarization and the charge asymmetry: fL(B+→ρ+K*0)=0. 52±0.10±0.04, fL(B0→ρ0K*0)=0.57±0. 09±0.08, ACP(B+→ρ+K*0)=-0.01±0.16±0.02, ACP(B0→ρ0K*0)=0.09±0.19±0.02, and ACP(B+→f0(980)K*+)=-0.34±0.21±0.03. © 2006 The American Physical Society.

Abstract:

We present measurements of the flavor-changing neutral current decays B→K + - and B→K* + -, where + - is either an e+e- or μ+μ- pair. The data sample comprises 229×106Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II e+e- storage ring. Flavor-changing neutral current decays are highly suppressed in the standard model and their predicted properties could be significantly modified by new physics at the electroweak scale. We measure the branching fractions B(B→K + -)=(0.34±0.07±0.02)×10-6, B(B→K* + -)=(0.78-0.17+0.19±0.11)×10-6, the direct CP asymmetries of these decays, and the relative abundances of decays to electrons and muons. For two regions in + - mass, above and below mJ/ψ, we measure partial branching fractions and the forward-backward angular asymmetry of the lepton pair. In these same regions we also measure the K* longitudinal polarization in B→K* + - decays. Upper limits are obtained for the lepton-flavor-violating decays B→Keμ and B→K*eμ. All measurements are consistent with standard model expectations. © 2006 The American Physical Society.