LHCb

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.

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.