Measurement of the semileptonic branching fraction of the B_s meson

We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BABAR detector in the center-of-mass energy region above the Υ(4S) resonance. We use the inclusive yield of ϕ mesons and the ϕ yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of center-of-mass energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s→ℓνX)=9.5_(-2.0)^(+2.5)(stat)_(-1.9)^(+1.1)(syst)%, where ℓ indicates the average of e and μ

B^0 meson decays to ρ^0K^(*0), f_0K^(*0), and ρ^-K^(*+), including higher K^* resonances

We present branching fraction measurements for the decays B^0→ρ^0K^(*0), B^0→f_0K^(*0), and B^0→ρ^-K^(*+), where K^* is an S-wave (Kπ)_0^* or a K^*(892) meson; we also measure B^0→f_0K_2^*(1430)^0. For the K^*(892) channels, we report measurements of longitudinal polarization fractions (for ρ final states) and direct CP violation asymmetries. These results are obtained from a sample of (471.0±2.8)×10^6 BB̅ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at the SLAC National Accelerator Laboratory. We observe ρ^0K^*(892)^0, ρ^0(Kπ)_0^(*0), f_0K^*(892)^0, and ρ^-K^*(892)^+ with greater than 5σ significance, including systematics. We report first evidence for f_0(Kπ)_0^(*0) and f_0K_2^*(1430)^0, and place an upper limit on ρ^-(Kπ)_0^(*+). Our results in the K^*(892) channels are consistent with no direct CP violation

Observation of the baryonic B decay B̅^0→Λ_c^+Λ̅ K^-

We report the observation of the baryonic B decay B̅ ^0→Λ_c^+Λ̅ K^- with a significance larger than 7 standard deviations based on 471×10^6 BB̅ pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. We measure the branching fraction for the decay B̅ ^0→Λ_c^+Λ̅ K^- to be (3.8±0.8_(stat)±0.2_(sys)±1.0_(Λc)^+)×10^(-5). The uncertainties are statistical, systematic, and due to the uncertainty in the Λc+ branching fraction. We find that the Λ_c^+K^- invariant-mass distribution shows an enhancement above 3.5  GeV/c^2

Search for the decay D^0 → γγ and measurement of the branching fraction for D^0 → π^0π^0

We search for the rare decay of the D^0 meson to two photons, D^0→γγ, and present a measurement of the branching fraction for a D^0 meson decaying to two neutral pions, B(D^0→π^0π^0). The data sample analyzed corresponds to an integrated luminosity of 470.5  fb^(-1) collected by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at SLAC. We place an upper limit on the branching fraction, B(D^0→γγ)<2.2×10^(-6), at 90% confidence level. This limit improves on the existing limit by an order of magnitude. We also find B(D^0→π^0π^0)=(8.4±0.1±0.4±0.3)×10^(-4)

Search for CP violation in the decay τ-→π-K_S^0(≥0π^0)ν_τ

We report a search for CP violation in the decay τ-→π-KS^0(≥0π^0)ντ using a data set of 437×10^6 τ-lepton pairs, corresponding to an integrated luminosity of 476  fb^(-1), collected with the BABAR detector at the PEP-II asymmetric-energy e^+e^- storage rings. The CP-violating decay-rate asymmetry is determined to be (-0.36±0.23±0.11)% approximately 2.8 standard deviations from the standard model prediction of (0.36±0.01)%