We report the results of a study of the decays B^+ -> J/psi omega K^+ and B^0 -> J/psi omega K_S^0 using 383 million B Bbar events from Y4S decays with the BABAR detector at the PEP-II ...asymmetric-energy e^+ e^- storage rings. We observe evidence for Y(3940) -> J/psi omega with product branching fractions B(B^+ -> Y K^+, Y -> J/psi omega) = (4.9 +- 1.0 (stat) +- 0.5 (syst)) * 10^{-5} and B(B^0 -> Y K^0, Y -> J/psi omega) = (1.5 ^{+1.4}_{-1.2} (stat) ^{+0.2}_{-0.2} (syst))* 10^{-5}. The measured mass and width are M(Y)= (3914.6 ^{+3.8}_{-3.4} (stat) ^{+1.9}_{-1.9} (syst)) MeV/c^2 and \Gamma (Y)= (33^{+12}_{-8}(stat)^{+5}_{-5}(syst)) MeV, respectively.
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Using 230.2 fb^(-1) of e+e- annihilation data collected with the BABAR detector at and near the peak of the Y(4S) resonance, 489 +/- 55 events containing the pure leptonic decay D_s^+ --> mu^+ nu_mu ...have been isolated in charm-tagged events. The ratio of partial widths Gamma(D_s^+ --> mu^+ nu_mu)/Gamma(D_s^+ --> phi pi^+) is measured to be 0.143 +/- 0.018 +/- 0.006 allowing a determination of the pseudoscalar decay constant f_{D_s} = (283 +/- 17 +/- 7 +/- 14) MeV. The errors are statistical, systematic, and from the D_s^+ --> phi pi^+ branching ratio, respectively.
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We present a measurement of the branching fraction and time-dependent CP asymmetry of B^0 to rho^0 K^0. The results are obtained from a data sample of 227 10^6 Y4S to BB_ decays collected with the ...BaBar detector at the PEP2 asymmetric-energy B Factory at SLAC. From a time-dependent maximum likelihood fit yielding 111+/-19 signal events we find B(B^0 to rho^0 K^0)=(4.9+/-0.8+/-0.9) 10^-6, where the first error is statistical and the second systematic. We report the measurement of the CP parameters S=0.20+/-0.52+/-0.24 and C=0.64+/-0.41+/-0.20.
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We present measurements of the time-dependent CP-violation parameters S and C in B^0 --> eta' K^0 decays. The data sample corresponds to 384 million B Bar pairs produced by e^+ e^- annihilation at ...the Y(4S). The results are S = 0.58 +- 0.10 +- 0.03 and C = -0.16 +- 0.07 +- 0.03. We observe mixing-induced CP violation with a significance of 5.5 standard deviations in this b -> s penguin dominated mode.
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We report the results of a study of the exclusive charmless semileptonic decay, B --> pi l nu, undertaken with approximately 227 million BBbar pairs collected at the Upsilon(4S) resonance with the ...BaBar detector. The analysis uses events in which the signal B decays are reconstructed with an innovative loose neutrino reconstruction technique. We obtain partial branching fractions in 12 bins of q2, the momentum transfer squared, from which we extract the f+(q2) form-factor shape and the total branching fraction BF(B0 --> pi l nu) = (1.46 +- 0.07(stat) +- 0.08(syst)) x 10^-4. Based on a recent unquenched lattice QCD calculation of the form factor in the range q2 > 16 GeV^2, we find the magnitude of the CKM matrix element |Vub| to be (4.1 +- 0.2(stat) +- 0.2(syst) +0.6-0.4(FF)) x 10^-3, where the last uncertainty is due to the normalization of the form factor.
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We present a search for the lepton flavor violating decay B+ --> K+ tau-/+ mu+/- using 383 million B Bbar events collected by the BABAR experiment. The branching fraction for this decay can be ...substantially enhanced in new physics models. The kinematics of the tau from the signal B decay are inferred from the K+, mu, and other B in the event, which is fully reconstructed in one of a variety of hadronic decay modes, allowing the signal B candidate to be fully reconstructed. We observe no excess of events over the expected background and set a limit of B(B+ --> K+ tau mu) < 7.7 x 10^-5 at 90% confidence level, where the branching fraction is for the sum of the K+ tau- mu+ and K+ tau+ mu- final states.
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We report a measurement of the time-dependent CP-asymmetry parameters $\cal S$ and $\cal C$ in color-suppressed $B^0 \to D^{(*)0} h^0$ decays, where $h^0$ is a $\pi^0$, $\eta$, or $\omega$ meson, and ...the $D^0$ decays to one of the CP eigenstates $K^+K^-$, $K_S\pi^0$, or $K_S\omega$. The data sample consists of $383\times 10^{6}$ $\Upsilon(4S)\to B\bar{B}$ decays collected with the BABAR detector at the PEP-II asymmetric-energy $B$-factory at SLAC. The results are ${\cal S}= -0.56 \pm 0.23 \pm 0.05$ and ${\cal C}= -0.23\pm 0.16\pm 0.04$, where the first error is statistical and the second is systematic.
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We search for the decays B0->rho0rho0, B0->rho0f0, and B0->f0f0 in a sample of about 384 million Upsilon(4S)->BBbar decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- ...collider at SLAC. We find evidence for B0->rho0rho0 with 3.5 sigma significance and measure the branching fraction BR = (1.07+-0.33+-0.19)10^-6 and longitudinal polarization fraction f_L = 0.87+-0.13+-0.04, where the first uncertainty is statistical, and the second is systematic. The uncertainty on the CKM unitarity angle alpha due to penguin contributions in B-> rho rho decays is 18 degrees at the 1 sigma level. We also set upper limits on the B0->rho0f0 and B0->f0f0 decay rates.
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We report the results of a CP violation analysis of the decay B+/- --> D(pipipi0)K+/-, where D(pipipi0) indicates a neutral D meson detected in the final state pi+pi-pi0, excluding K_S pi0. The ...analysis makes use of 324 million e+e- --> BB events recorded by the BaBar experiment at the PEP-II e+e- storage ring. By analyzing the pi+pi-pi0 Dalitz plot distribution and the B+/- --> D(pipipi0)K+/- branching fraction and decay rate asymmetry, we calculate parameters related to the phase gamma of the CKM unitarity triangle. We also measure the magnitudes and phases of the components of the D0 --> pi+pi-pi0 decay amplitude.
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