11 research outputs found
Angular distributions in the decay B -> K*l(+)l(-)
We use a sample of 384 million BBbar events collected with the Babar detector at the PEP-II e+e- collider to study angular distributions in the rare decays B -> K* l+l-, where l+l- is either e+e- or mu+mu-. For low dilepton invariant masses, m(l+l-)3.2$ GeV/c^2, we measure AFB=0.76 (+0.52,-0.32) +/- 0.07 FL=0.71 (+0.20,-0.22) +/- 0.04.We are grateful for the excellent luminosity and machine
conditions provided by our PEP-II colleagues, and
for the substantial dedicated effort from the computing
organizations that support BABAR. The collaborating
institutions wish to thank SLAC for its support and
kind hospitality. This work is supported by DOE and
NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3
(France), BMBF and DFG (Germany), INFN (Italy),
FOM (The Netherlands), NFR (Norway), MES (Russia),
MEC (Spain), and STFC (United Kingdom). Individuals
have received support from the Marie Curie EIF (European
Union) and the A. P. Sloan Foundation.Peer reviewe
Measurements of the Branching Fractions of , and
8 pages, 2 postscript figures, submitted to Lepton Photon 2007A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using 376 fb^{-1} of data collected at an e^+e^- center-of-mass energy around 10.58 GeV with the BaBar detector at the PEP-II storage rings. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (4-8) x 10^{-8} at 90% confidence level
Measurement of the B→Xsγ branching fraction and photon energy spectrum using the recoil method
We present a measurement of the branching fraction and photon-energy spectrum for the decay B→Xsγ using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210 fb-1, from which approximately 680 000 BB̅ events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high-energy photon is identified. We measure B(B→Xsγ)=(3.66±0.85stat±0.60syst)×10-4 for photon energies Eγ above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters mb and μπ2. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented
Скорейшее обнаружение разладки авторегрессионных процессов при неизвестной конечной модели
7 pages, 8 postscript figures, submitted to PRLWe present evidence of - mixing using a time-dependent amplitude analysis of the decay D0->K+pi-pi0 in a data sample of 384 fb^-1 collected with the BaBar detector at the PEP-II e+e- collider at SLAC. Assuming CP conservation, we measure the mixing parameters x'_{Kpipi0} = [2.61^{+0.57}_{-0.68} (stat.) +- 0.39 (syst.)]%, y'_{Kpipi0} = [-0.06 ^{+0.55}_{-0.64} (stat.) +- 0.34 (syst.)]%. The confidence level for the data to be consistent with the no-mixing hypothesis is 0.1%, including systematic uncertainties. 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
Model-independent search for the decay B^{+}→l^{+}ν_{l}γ
We present a search for the radiative leptonic decay B(+)-> l(+)nu(l)gamma, where l=e, mu, using a data sample of 465x10(6) BB pairs collected by the BABAR experiment. In this analysis, we fully reconstruct the hadronic decay of one of the B mesons in Upsilon(4S)-> B(+)B(-) decays, then search for evidence of B(+)-> l(+)nu(l)gamma in the rest of the event. We observe no significant evidence of signal decays and report model-independent branching fraction upper limits of B(B(+)-> e(+)nu(e)gamma)mu(+)nu(mu)gamma) l(+)nu(l)gamma)< 15.6x10(-6) (l=e or mu), all at the 90% confidence level
B meson decays to charmless meson pairs containing eta or eta' mesons
We present updated measurements of the branching fractions for B-0 meson decays to eta K-0, eta eta, eta phi, eta omega, eta K-'(0), eta(')eta('), eta(')phi, and eta(')omega, and branching fractions and CP-violating charge asymmetries for B+ decays to eta pi(+), eta K+, eta(')pi(+), and eta K-'(+). The data represent the full data set of 467x10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decay modes and for B-0 ->eta K-'(0), we find evidence for three B-0 decay modes at greater than 3.0 sigma significance. We find B(B-0 ->eta K-0)=(1.15(-0.38)(+0.43)+/- 0.09)x10(-6), B(B-0 ->eta omega)=(0.94(-0.30)(+0.35)+/- 0.09)x10(-6), and B(B-0 ->eta(')omega)=(1.01(-0.38)(+0.46)+/- 0.09)x10(-6), where the first (second) uncertainty is statistical (systematic). For the B+->eta K+ decay mode, we measure the charge asymmetry A(ch)(B+->eta K+)=-0.36 +/- 0.11 +/- 0.03
Observation of the baryonic B-decay B0bar -> Lambda_c^+ antiproton K^- pi^+
7 pages, 3 postscript figures, submitted to PRD RC; BABAR-PUB-09/014, SLAC-PUB-13675We report the observation of the baryonic B-decay B0bar -> Lambda_c^+ antiproton K^- pi^+, excluding contributions from the decay B0bar -> Lambda_c^+ anti-Lambda K^-. Using a data sample of 467*10^6 BBbar pairs collected with the BABAR detector at the PEP-II storage ring at SLAC, the measured branching fraction is (4.33 +/- 0.82_stat +/- 0.33_syst +/- 1.13_Lambda_c^+)*10^-5. In addition we find evidence for the resonant decay B0bar -> Sigma_c(2455)^++ antiproton K^- and determine its branching fraction to be (1.11 +/- 0.30_stat +/- 0.09_syst +/- 0.29_Lambda_c^+)*10^-5. The errors are statistical, systematic, and due to the uncertainty in the Lambda_c^+ branching fraction. For the resonant decay B0bar -> Lambda_c^+ antiproton K^*0 we obtain an upper limit of 2.42*10^-5 at 90% confidence level
Measurement and interpretation of moments in inclusive semileptonic decays (B)over-bar -> Xcl(nu)over-bar
We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons (B) over bar -> X(c)l(-)(nu) over bar. Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1: 9 GeV/c are obtained from a sample of 232 X 10(6) Gamma(4S) -> B (B) over bar events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a reevaluation of the moments of electron-energy spectra and partial decay fractions B((B) over bar -> X(c)e(-)(nu) over bar) for minimum electron momenta between 0.6 and 1: 5 GeV/c based on a sample of 51 X 10(6) Gamma(4S) -> B (B) over bar events. The measurements are used for the extraction of the total decay fraction, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element vertical bar V-cb vertical bar, the quark masses m(b) and m(c), and four heavy-quark QCD parameters in the framework of a Heavy-Quark Expansion (HQE). We find B((B) over bar -> X(c)l(-)(nu) over bar = (10.64 +/- 0.17 +/- 0.06)% and vertical bar V-cb vertical bar = (42.05 +/- 0.45 +/- 0.70) X 10(-3)
Search for b -> u transitions in B-0 -> (DK)-K-0*(0) decays
We present a study of the decays B-0 -> (DK)-K-0*(0) and B-0 -> (D) over bar K-0*(0) and K*(0) -> K+pi(-). The D-0 and the (D) over bar (0) mesons are reconstructed in the final states f = K+pi(-), K+pi(-)pi(0), K+pi(-)pi(+)pi(-), and their charge conjugates. Using a sample of 465 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC, we measure the ratio R-ADS = [Gamma((B) over bar -> [f] (K) over bar (0)) + Gamma(B-0 -> [(f) over bar K-D*(0))]/[Gamma((B) over bar (0) -> [(f) over bar (D)(K)over bar>*(0))] + Gamma(B-0 -> [f](D)K*(0))] for the three final states. We do not find significant evidence for a signal and set the following limits at 95% probability: R-ADS (K pi) u and the b -> c amplitudes lies in the range [0.07,0.41] at 95% probability
Search for second-class currents in tau(-) -> omega pi(-)nu(tau)
We report an analysis of tau(-) decaying into omega pi(-)nu(tau) with omega -> pi(+)pi(-)pi(0) using a data sample containing nearly 320 x 10(6)tau pairs collected with the BABAR detector at the PEP-II B-Factory. We find no evidence for second-class currents, and we set an upper limit of 0.69% at 90% confidence level for the fraction of second-class currents in this decay mode