Measurement of the spectral function for the τ^− → K^−K_Sν_τ decay

The decay τ^− → K^−K_Sν_τ has been studied using 430×10^6 e^+e^− → τ^+τ^− events produced at a center-of-mass energy around 10.6 GeV at the PEP-II collider and studied with the BABAR detector. The mass spectrum of the K^−K_S system has been measured and the spectral function has been obtained. The measured branching fraction B(τ^− → K^−K_Sν_τ) = (0.739 ± 0.011(stat) ± 0.020(syst)) × 10^(-3) is found to be in agreement with earlier measurements

Search for lepton-flavor-violating decays D⁰ → X⁰e±μ∓

We present a search for seven lepton-flavor-violating neutral charm meson decays of the type D⁰ → X⁰e±μ∓, where X⁰ represents a π⁰, K⁰_S, K*⁰, ρ⁰, ϕ, ω, or η meson. The analysis is based on 468  fb⁻¹ of e⁺e⁻ annihilation data collected at or close to the Υ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signals are observed, and we establish 90% confidence level upper limits on the branching fractions in the range (5.0−22.5) × 10⁻⁷. The limits are between 1 and 2 orders of magnitude more stringent than previous measurements

Study of Υ(1S) radiative decays to γπ^+π^− and γK^+K^−

We study the Υ(1S) radiative decays to γπ^+π^− and γK^+K^− using data recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e^+e^− collider at center-of-mass energies at the Υ(2S) and Υ(3S) resonances. The Υ(1S) resonance is reconstructed from the decay Υ(nS)→π^+π^−Υ(1S), n=2, 3. Branching fraction measurements and spin-parity analyses of Υ(1S)radiative decays are reported for the I=0 S-wave and f_2(1270) resonances in the π^+π^− mass spectrum, the f′_2(1525) and f_0(1500) in the K^+K^− mass spectrum, and the f_0(1710) in both

Measurement of the e^+e^− → K^0_sK^±π^∓π^0 and K^0_sK^±π^∓η cross sections using initial-state radiation

The processes e^+e^− → K^0_SK^±π^∓π^0 and e^+e^− → K^0_SK^±π^∓η are studied over a continuum of energies from threshold to 4 GeV with the initial-state photon radiation method. Using 454  fb^(-1) of data collected with the BABAR detector at the SLAC PEP-II storage ring, the first measurements of the cross sections for these processes are obtained. The intermediate resonance structures from K^(*0)(Kπ)^0, K^∗(892)^±(Kπ)^∓ , and K^0_SK^±ρ^∓ are studied. The J/ψ is observed in all of these channels, and corresponding branching fractions are measured

Study of the process e^+e^− → π^+π^−η using initial state radiation

We study the process e^+e^− → π^+π^−ηγ, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BABAR data sample with an integrated luminosity of 469  fb^(-1). Using the π^+π^−η invariant mass spectrum, we measure the e^+e^− → π^+π^−η cross section in the e^+e^− center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson dominance model with four ρ-like states. We observe 49±9 events of the J/ψ decay to π^+π^−η and measure the product Γ_(J/Ψ → e^+e^−)B_(J/Ψ → π^+π^−η) = 2.34 ± 0.43_(stat) ± 0.16_(syst)  eV