14 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
Measurement of the γγ*→π0 transition form factor
We study the reaction e + e − → e + e − π 0 in the single tag mode and measure the differential cross section d σ / d Q 2 and the γ γ ∗ → π 0 transition form factor in the momentum transfer range from 4 to 40 GeV 2 . At Q 2 > 10 GeV 2 the measured form factor exceeds the asymptotic limit predicted by perturbative QCD. The analysis is based on 442 fb − 1 of integrated luminosity collected at PEP-II with the BABAR detector at e + e − center-of-mass energies near 10.6 GeV
Unsaturated σ-hydrocarbyl transition-metal complexes. Part 2. Synthesis and reactions of vinylplatinum complexes and a comparison with analogous fluorovinyl and alkynyl complexes
Alkenyl (CHCH2 or CFCF2) or alkynyl (CCPh) derivatives of trimethyltin are shown to be superior to lithium or magnesium reagents for the synthesis of corresponding mono-organoplatinum(II) species by metathesis (L = SnMe3R +cis-[PtCl2L2]→trans-[PtRClL2]+ SnMe3Cl tertiary phosphine). The reactivity order for SnMe3R is R = CCPh > CFCF2 > CHCH2. This order is also found for oxidative addition of SnMe3R to Pt0 to give cis-[PtRL2(SnMe3)]. When the latter complex (R = CHCH2) reacts with X2 or MeX further oxidative addition occurs exclusively at the platinum centre. Aromatic isonitriles (R′NC)co-ordinate to the platinum and give insertion products trans-[Pt{C(CHCH2)= NR′}ClL2] on heating or carbene complexes with NBunH2. The alkynyl trans-[Pt(CCPh)ClL2] also forms 1 :1 adducts with R′NC and carbene complexes therefrom, but no insertion products. Spectroscopic data for the new complexes are presented
Exclusive production of D_{s}^{+}D_{s}^{-}, D_{s}^{*+}D_{s}^{-}, and D_{s}^{*+}D_{s}^{*-} via e^{+}e^{-} annihilation with initial-state radiation
We perform a study of exclusive production of Ds+Ds-, Ds*+Ds-, and Ds*+Ds*- final states in initial-state-radiation events from e+e- annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium 1-- states. The data sample corresponds to an integrated luminosity of 525 fb-1 and was recorded by the BABAR experiment at the PEP-II storage ring. The Ds+Ds-, Ds*+Ds-, and Ds*+Ds*- mass spectra show evidence of the known ψ resonances. Limits are extracted for the branching ratios of the decays X(4260)→Ds(*)+Ds(*)-
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
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
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
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)