We present measurements of the semileptonic decays B- --> D0 tau- nubar, B- --> D*0 tau- nubar, B0bar --> D+ tau- nubar, and B0bar --> D*+ tau- nubar, which are potentially sensitive to non--Standard ...Model amplitudes. The data sample comprises 232x10^6 Upsilon(4S) --> BBbar decays collected with the BaBar detector. From a combined fit to B- and B0bar channels, we obtain the branching fractions B(B --> D tau- nubar) = (0.86 +/- 0.24 +/- 0.11 +/- 0.06)% and B(B --> D* tau- nubar) = (1.62 +/- 0.31 +/- 0.10 +/- 0.05)% (normalized for the B0bar), where the uncertainties are statistical, systematic, and normalization-mode-related.
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.
We report a measurement of the branching fractions for Bbar -> D(*)(pi)l-nubar decays based on 341.1 fb-1 of data collected at the Upsilon(4S) resonance with the babar detector at the PEP-II e+e- ...storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We obtain B(B- -> D0l-nubar) = (2.33 +/- 0.09(stat.) +/- 0.09(syst.))%, B(B- -> D*0l-nubar) = (5.83 +/- 0.15(stat.) +/- 0.30(syst.))%, B(B0bar -> D+l-nubar) = (2.21 +/- 0.11(stat.) +/- 0.12(syst.))%, B(B0bar -> D*+l-nubar) = (5.49 +/- 0.16(stat.) +/- 0.25(syst.))%, B(B- -> D+pi-l-nubar) = (0.42 +/- 0.06(stat.) +/- 0.03(syst.))%, B(B- -> D*+pi-l-nubar) = (0.59 +/- 0.05(stat.) +/- 0.04(syst.))%, B(B0bar -> D0pi+l-nubar) = (0.43 +/- 0.08(stat.) +/- 0.03(syst.))%, and B(B0bar -> D*0pi+l-nubar) = (0.48 +/- 0.08(stat.) +/- 0.04(syst.))%.
We present partial branching fractions for inclusive charmless semileptonic B decays Bbar --> X_u ell nubar, and the determination of the CKM matrix element |V_{ub}|. The analysis is based on a ...sample of 383 million Y(4S) decays into B Bbar pairs collected with the BaBar detector at the PEP-II e+ e- storage rings. We select events using either the invariant mass M_X of the hadronic system, the invariant mass squared, q^2, of the lepton and neutrino pair, the kinematic variable P_+ or one of their combinations. We then determine partial branching fractions in limited regions of phase space: Delta B = (1.18 +- 0.09_{stat.} +- 0.07_{sys.} +- 0.01_{theo.}) x 10^{-3} (M_X < 1.55 GeV/c^2), Delta B = (0.95 +- 0.10_{stat.} +- 0.08_{sys.} +- 0.01_{theo.}) x 10^{-3} (P_+ < 0.66 GeV/c), and Delta B = (0.76 +- 0.08_{stat.} +- 0.07_{sys.} +- 0.02_{theo.}) x 10^{-3} (M_X < 1.7 GeV/c^2, q^2 > 8 GeV^2/c^4). Corresponding values of |V_{ub}| are extracted using several theoretical calculations.
Using 226 million $B\bar{B}$ events recorded on the $\Upsilon(4S)$ resonance with the BABAR detector at the SLAC $e^+e^-$ PEPII storage rings, we reconstruct $B^- \to D^{*0} e^-\bar{\nu}_e$ decays ...using the decay chain $D^{*0} \to D^0\pi^0$ and $D^0 \to K^-\pi^+$. From the $w$ dependence of their differential rate, and using the form factor description by Caprini et al., we obtain the results $\rho_{A_1}^2 = 1.16\pm 0.06 \pm 0.08$, $F(1)\cdot|V_{cb}| =(35.9\pm 0.6 \pm 1.4)\cdot 10^{-3}$, and ${\cal{B}}(B^- \to D^{*0}e^-\bar{\nu}_e) = (5.56\pm 0.08\pm 0.41)%$.
We present branching fraction measurements of the decays B^{+} -> a1(1260)^{+} K^{0} and B^{0} to a1(1260)^{-} K^{+} with a1(1260)^{+} -> pi^{-} pi^{+} pi^{+}. The data sample corresponds to 383 ...million B B-bar pairs produced in e^{+}e^{-} annihilation through the Y(4S) resonance. We measure the products of the branching fractions: B(B^{+}-> a1(1260)^{+} K^{0})B(a1(1260)^{+} -> pi^{-} pi^{+} pi^{+}) = (17.4 +/- 2.5 +/- 2.2) 10^{-6} B(B^{0}-> a1(1260)^{-} K^{+})B(a1(1260)^{-} -> pi^{+} pi^{-} pi^{-}) = (8.2 +/- 1.5 +/- 1.2) 10^{-6}. We also measure the charge asymmetries A_{ch}(B^{+} -> a1(1260)^{+} K^{0})= 0.12 +/- 0.11 +/- 0.02 and A_{ch}(B^{0} -> a1(1260)^{-} K^{+})= -0.16 +/- 0.12 +/- 0.01. The first uncertainty quoted is statistical and the second is systematic.
We have searched for lepton flavor violating decays of a $\tau$ to a lighter-mass charged lepton and an $\omega$ vector mesonusing 384.1 $fb^{-}$ of $e^+e^- $ annihilation data collected with the ...BABAR detector at the Stanford Linear Accelerator Center PEP-II storage ring. No signal is found, and the upper limits on the branching ratios are determined to be ${\cal B}(\tau^{\pm} \to \mathrm{e}^{\pm} \omega) < 1.1\times10^{-7}$ and ${\cal B}(\tau^{\pm} \to \mu^{\pm} \omega) < 1.0\times10^{-7}$ at 90% confidence level.
We report measurements of branching fractions for the decays B --> P l nu, where P are the pseudoscalar charmless mesons pi-, pi0, eta and eta', based on 348 fb-1 of data collected with the BABAR ...detector, using B0 and B+ mesons found in the recoil of a second B meson decaying as B --> D(*) l nu. Assuming isospin symmetry, we combine pionic branching fractions to obtain B(B0 --> pi- l+ nu) = (1.54 +/- 0.17(stat) +/- 0.09(syst)) x 10-4; we find 3.2 sigma evidence of the decay B+ --> eta l+ nu and measure its branching fraction to be (0.64 +/- 0.20 (stat) +/- 0.03 (syst)) x 10-4, and determine B(B+ --> eta' l+ nu) < 0.47 x 10-4 to 90% confidence level. Using partial branching fractions for the pionic decays in ranges of the momentum transfer and a recent form factor calculation, we obtain the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| = (4.0 +/- 0.5(stat) +/- 0.2(syst) +0.7-0.5(theory)) x 10-3.
We report results of a search for CPT and Lorentz violation in B0-B0bar oscillations using inclusive dilepton events from 232 million Y(4S) --> BBbar decays recorded by the BABAR detector at the ...PEP-II B Factory at SLAC. We find 2.8sigma significance, compatible with no signal, for variations in the complex CPT violation parameter z at the Earth's sidereal frequency and extract values for the quantities \Delta(a_\mu) in the general Lorentz-violating standard-model extension. The spectral powers for variations in z over the frequency range 0.26/year to 2.1/day are also compatible with no signal.
We present the results of searches for B decays to charmless final states involving phi, fzero(980), and charged or neutral rho mesons. The data sample corresponds to 384 million BBbar pairs ...collected with the babar detector operating at the PEP-II asymmetric-energy epem 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(B0->phiphi) < 2.0 x 10^-7, B(B+->phirho+) < 30 x 10^-7, B(B0->phirho0) < 3.3 x 10^-7, B(B0-phif0) x B(f0->pi+pi-) < 3.8 x 10^-7, and B(B0->f0f0) x B(f0->pi+pi-) x B(f0->K+K-) < 2.3 x 10^-7
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