410 research outputs found

    Measurements of the absolute branching fractions of B+XccˉK+B^{+} \to X_{c\bar{c}} K^{+} and B+Dˉ()0π+B^{+} \to \bar{D}^{(\ast) 0} \pi^{+} at Belle

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    We present the measurement of the absolute branching fractions of B+XccˉK+B^{+} \to X_{c\bar{c}} K^{+} and B+Dˉ()0π+B^{+} \to \bar{D}^{(\ast) 0} \pi^{+} decays, using a data sample of 772×106772\times10^{6} BBˉB\bar{B} pairs collected at the Υ(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ee^{+}e^{-} collider. Here, XccˉX_{c\bar{c}} denotes ηc\eta_{c}, J/ψJ/\psi, χc0\chi_{c0}, χc1\chi_{c1}, ηc(2S)\eta_{c}(2S), ψ(2S)\psi(2S), ψ(3770)\psi(3770), X(3872)X(3872), and X(3915)X(3915). We do not observe significant signals for X(3872)X(3872) nor X(3915)X(3915), and set the 90%\% confidence level upper limits: B(B+X(3872)K+)<2.7×104{\cal B}(B^{+} \to X(3872) K^{+} )<2.7 \times 10^{-4} and B(B+X(3915)K+)<2.9×104{\cal B}(B^{+} \to X(3915) K^{+} )<2.9 \times 10^{-4}. These represent the most stringent upper limit for B(B+X(3872)K+){\cal B}(B^{+} \to X(3872) K^{+} ) to date and the first measurement for B(B+X(3915)K+){\cal B}(B^{+} \to X(3915) K^{+} ). The measured branching fractions for ηc\eta_{c} and ηc(2S)\eta_{c}(2S) are the most precise to date: B(B+ηcK+)=(12.3±0.8±0.7)×104{\cal B}(B^{+} \to \eta_{c} K^{+} )=(12.3\pm0.8\pm0.7) \times 10^{-4} and B(B+ηc(2S)K+)=(4.9±1.1±0.3)×104{\cal B}(B^{+} \to \eta_{c}(2S)K^{+}) =(4.9\pm1.1\pm0.3) \times 10^{-4} , where the first and second uncertainties are statistical and systematic, respectively.Comment: 10 pages, 3 figure

    Study of CP violation in Dalitz-plot analyses of B0 --> K+K-KS, B+ --> K+K-K+, and B+ --> KSKSK+

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    We perform amplitude analyses of the decays B0K+KKS0B^0 \to K^+K^-K^0_S, B+K+KK+B^+ \rightarrow K^+K^-K^+, and B+KS0KS0K+B^+ \to K^0_S K^0_S K^+, and measure CP-violating parameters and partial branching fractions. The results are based on a data sample of approximately 470×106470\times 10^6 BBˉB\bar{B} decays, collected with the BABAR detector at the PEP-II asymmetric-energy BB factory at the SLAC National Accelerator Laboratory. For B+K+KK+B^+ \to K^+K^-K^+, we find a direct CP asymmetry in B+ϕ(1020)K+B^+ \to \phi(1020)K^+ of ACP=(12.8±4.4±1.3)A_{CP}= (12.8\pm 4.4 \pm 1.3)%, which differs from zero by 2.8σ2.8 \sigma. For B0K+KKS0B^0 \to K^+K^-K^0_S, we measure the CP-violating phase βeff(ϕ(1020)KS0)=(21±6±2)\beta_{\rm eff} (\phi(1020)K^0_S) = (21\pm 6 \pm 2)^\circ. For B+KS0KS0K+B^+ \to K^0_S K^0_S K^+, we measure an overall direct CP asymmetry of ACP=(45+4±2)A_{CP} = (4 ^{+4}_{-5} \pm 2)%. We also perform an angular-moment analysis of the three channels, and determine that the fX(1500)f_X(1500) state can be described well by the sum of the resonances f0(1500)f_0(1500), f2(1525)f_2^{\prime}(1525), and f0(1710)f_0(1710).Comment: 35 pages, 68 postscript figures. v3 - minor modifications to agree with published versio

    First Observation of CP Violation in B0->D(*)CP h0 Decays by a Combined Time-Dependent Analysis of BaBar and Belle Data

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    We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.Comment: 9 pages, 2 figures, submitted to Physical Review Letter

    Improved Limits on B0B^{0} decays to invisible (+γ)(+\gamma) final states

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    We establish improved upper limits on branching fractions for B0 decays to final States 10 where the decay products are purely invisible (i.e., no observable final state particles) and for final states where the only visible product is a photon. Within the Standard Model, these decays have branching fractions that are below the current experimental sensitivity, but various models of physics beyond the Standard Model predict significant contributions for these channels. Using 471 million BB pairs collected at the Y(4S) resonance by the BABAR experiment at the PEP-II e+e- storage ring at the SLAC National Accelerator Laboratory, we establish upper limits at the 90% confidence level of 2.4x10^-5 for the branching fraction of B0-->Invisible and 1.7x10^-5 for the branching fraction of B0-->Invisible+gammaComment: 8 pages, 3 postscript figures, submitted to Phys. Rev. D (Rapid Communications

    Measurement of Branching Fractions and Rate Asymmetries in the Rare Decays B -> K(*) l+ l-

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    In a sample of 471 million BB events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B -> K(*) l+ l-, where l+ l- is either e+e- or mu+mu-. We report results on partial branching fractions and isospin asymmetries in seven bins of di-lepton mass-squared. We further present CP and lepton-flavor asymmetries for di-lepton masses below and above the J/psi resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.Comment: 16 pages, 14 figures, accepted by Phys. Rev.
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