246 research outputs found

    Evidence for the η_b(1S) Meson in Radiative Υ(2S) Decay

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    We have performed a search for the η_b(1S) meson in the radiative decay of the Υ(2S) resonance using a sample of 91.6 × 10^6 Υ(2S) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E_γ = 609.3^(+4.6)_(-4.5)(stat)±1.9(syst) MeV, corresponding to an η_b(1S) mass of 9394.2^(+4.8)_(-4.9)(stat) ± 2.0(syst) MeV/c^2. The branching fraction for the decay Υ(2S) → γη_b(1S) is determined to be [3.9 ± 1.1(stat)^(+1.1)_(-0.9)(syst)] × 10^(-4). We find the ratio of branching fractions B[Υ(2S) → γη_b(1S)]/B[Υ(3S) → γη_b(1S)]= 0.82 ± 0.24(stat)^(+0.20)_(-0.19)(syst)

    Measurement of D^0-D̅ ^0 Mixing from a Time-Dependent Amplitude Analysis of D^0→K^+π^-π^0 Decays

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    We present evidence of D^0-D̅ ^0 mixing using a time-dependent amplitude analysis of the decay D^0→K^+π^-π^0 in a data sample of 384  fb^(-1) collected with the BABAR detector at the PEP-II e^+e^- collider at the Stanford Linear Accelerator Center. Assuming CP conservation, we measure the mixing parameters x_(Kππ)^(0′)=[2.61_(-0.68)^(+0.57)(stat)±0.39(syst)]%, y_(Kππ)^(0′)=[-0.06_(-0.64)^(+0.55)(stat)±0.34(syst)]%. This result is inconsistent with the no-mixing hypothesis with a significance of 3.2 standard deviations. We find no evidence of CP violation in mixing

    Evidence for X(3872) → Ψ (2S)y in B^± → X(3872)K^± Decays and a Study of B → ccyK

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    In a search for B → ccyK decays with the BABAR detector, where cc includes J/Ψ and Ψ (2S), and K includes K^±, K^0_S , and K^*(892), we find evidence for X(3872) → J/Ψy and X(3872) → Ψ (2S) with 3:6σ and 3:5σ significance, respectively. We measure the product of branching fractions B(B^± → X(3872)K^±)B(X(3872) → J/Ψy)= [2:8 ± 0:8(stat) ± 0:1(syst)]X 10^(-6) and B(B^± → X(3872)K^±) X B(X(3872) → Ψ (2S)y) = [9:5 ± 2:7(stat) ± 0:6(syst)] X 10^(-6)

    Searches for B Meson Decays to ϕϕ, ϕρ, ϕf_0(980), and f_0(980)f_0(980) Final States

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    We present the results of searches for B decays to charmless final states involving ϕ, f_0(980), and charged or neutral ρ mesons. The data sample corresponds to 384×10^6 BB̅ pairs collected with the BABAR detector operating at the PEP-II asymmetric-energy e^̅+e^- collider at SLAC. We find no significant signals and determine the following 90% confidence level upper limits on the branching fractions, including systematic uncertainties: B(B^0→ϕϕ)<2.0×10^(-7), B(B+→ϕρ^+)<30×10^(-7), B(B^0→ϕρ^0)<3.3×10^(-7), B[B^0→ϕf_0(980)]×B[f_0(980)→π^+π^-]<3.8×10^(-7), and B[B^0→f_0(980)f_0(980)]×B[f_0(980)→π^+π^-]×B[f_0(980)→K^+K^-]<2.3×10^(-7)

    Measurement of the branching fractions of (B)over-bar -> D**l(-)(v)over-bar(l) decays in events tagged by a fully reconstructed B meson

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    We report a measurement of the branching fractions of D**- decays based on 417 fb-1 of data collected at the (4S) resonance with the BABAR detector at the PEP-II e+e- storage rings. Events are selected by fully reconstructing one of the B mesons in a hadronic decay mode. A fit to the invariant mass differences m(D(*))-m(D(*)) is performed to extract the signal yields of the different D** states. We observe the D**- decay modes corresponding to the four D** states predicted by heavy quark symmetry with a significance greater than 5 standard deviations including systematic uncertainties

    Measurements of branching fractions for B^+ → p^+γ, B^0 → p^0γ, and B^0 → ωγ

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    We present branching fraction measurements for the radiative decays B^+ → ρ^+ γ, B^0 → ρ^0 γ, and B^0 → ωγ. The analysis is based on a data sample of 465 × 10^6 B[overline B] events collected with the BABAR detector at the PEP-II asymmetric-energy B Factory located at the Stanford Linear Accelerator Center. We find [script B](B^+ → ρ^+ γ) = (1.20_(-0.37)^(+0.42) ± 0.20) × 10^(-6), [script B](B^0 → ρ^0γ) = (0.97_(-0.22)^(+0.24) ± 0.06) × 10^(-6), and a 90% C.L. upper limit [script B](B^0 → ωγ) < 0.9 × 10^(-6), where the first error is statistical and the second is systematic. We also measure the isospin-violating quantity Γ(B^+ → ρ^+ γ)/2Γ(B^0 → ρ^0γ)-1 = -0.43_(-0.22)^(+0.25)±0.10

    Measurement of time dependent CP asymmetry parameters in B0 meson decays to omegaK_S^0, eta^([prime])K^0, and pi^0K_S^0

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    We present measurements of the time-dependent CP-violation parameters S and C in the decays B0-->omegaKS0, B0-->eta[prime]K0, reconstructed as eta[prime]KS0 and eta[prime]KL0, and B0-->pi0KS0. The data sample corresponds to the full BABAR dataset of 467×106 B[overline B] pairs produced at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. The results are SomegaKS0=0.55-0.29+0.26±0.02, ComegaKS0=-0.52-0.20+0.22±0.03, Seta[prime]K0=0.57±0.08±0.02, Ceta[prime]K0=-0.08±0.06±0.02, Spi0KS0=0.55±0.20±0.03, and Cpi0KS0=0.13±0.13±0.03, where the first errors are statistical and the second systematic. These results are consistent with our previous measurements and the world average of sin2beta measured in B0-->J/psiKS0

    Observation of B^0 → χ_(c0)K^(*0) and evidence for B^+ → χ_(c0)K^(*+)

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    We present the observation of the decay B^0 → χ_(c0)K^(*0) as well as evidence of B^+ → χ_(c0)K^(*+), with an 8.9 and a 3.6 standard deviation significance, respectively, using a data sample of 454×10^6 Υ(4S) → B[overline B] decays collected with the BABAR detector at the PEP-II B meson factory located at the Stanford Linear Accelerator Center (SLAC). The measured branching fractions are [script B](B^0 → Χ_(c0)K^(*0))=(1.7±0.3±0.2)×10^(-4) and [script B](B^+ → Χ_(c0)K^(*+))=(1.4±0.5±0.2)×10^(-4), where the first quoted errors are statistical and the second are systematic. We obtain a branching fraction upper limit of [script B](B^+ → Χ_(c0)K^(*+))<2.1×10^(-4) at the 90% confidence level

    Study of hadronic transitions between Υ states and observation of Υ(4S) → ηΥ(1S) decay

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    We present a study of hadronic transitions between Υ(mS) (m = 4, 3, 2) and Υ(nS) (n = 2, 1) resonances based on 347.5 fb^(-1) of data taken with the BABAR detector at the PEP-II storage rings. We report the first observation of Υ(4S) → ηΥ(1S) decay with a branching fraction [script B](Υ(4S) → ηΥ(1S)) = (1.96±0.06_(stat)±0.09_(syst))×10^(-4) and measure the ratio of partial widths Γ(Υ(4S) → ηΥ(1S))/Γ(Υ(4S) → π^+π^-Υ(1S))=2.41±0.40_(stat)±0.12_(syst). We set 90% CL upper limits on the ratios Γ(Υ(2S) → ηΥ(1S))/Γ(Υ(2S) → π^+π^-Υ(1S))<5.2×10^(-3) and Γ(Υ(3S) → ηΥ(1S))/Γ(Υ (3S) → π^+π^-Υ(1S))<1.9×10^(-2). We also present new measurements of the ratios Γ(Υ(4S) → π^+π^-Υ(2S))/Γ(Υ(4S) → π^+ π^-Υ(1S))=1.16±0.16_(stat)±0.14_(syst) and Γ(Υ(3S) → π^+π^-Υ(2S))/Γ(Υ(3S) → π^+ π^-Υ(1S))=0.577±0.026_(stat)±0.060_(syst)
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