503 research outputs found

    Study of Lambda/c+ Cabibbo Favored Decays Containing a Lambda Baryon in the Final State

    Full text link
    Using data from the FOCUS experiment (FNAL-E831), we study the decay of Λc+\Lambda^+_c baryons into final states containing a Λ\Lambda hyperon. The branching fractions of Λc+\Lambda^+_c into Λπ+\Lambda \pi^+, Λπ+π+π−\Lambda \pi^+ \pi^+ \pi^- and ΛKˉ0K+\Lambda \bar{K} ^0 K^+ relative to that into pK−π+pK^-\pi^+ are measured to be 0.217±0.013±0.0200.217 \pm 0.013 \pm 0.020, 0.508±0.024±0.0240.508 \pm 0.024 \pm 0.024 and 0.142±0.018±0.0220.142 \pm 0.018 \pm 0.022, respectively. We also report new measurements of Γ(Λc+→Σ0π+)Γ(Λc+→Λπ+)=1.09±0.11±0.19\frac{\Gamma(\Lambda^+_c \to \Sigma^0 \pi^+)}{\Gamma(\Lambda^+_c \to \Lambda \pi^+)} = 1.09 \pm 0.11 \pm 0.19, Γ(Λc+→Σ0π+π+π−)Γ(Λc+→Λπ+π+π−)=0.26±0.06±0.09\frac{\Gamma(\Lambda^+_c \to \Sigma^0 \pi^+\pi^+ \pi^-)}{\Gamma(\Lambda^+_c \to \Lambda \pi^+ \pi^+ \pi^-)} = 0.26 \pm 0.06 \pm 0.09 and Γ(Λc+→Ξ(1690)0(ΛKˉ0)K+)Γ(Λc+→ΛKˉ0K+)=0.33±0.10±0.04\frac{\Gamma(\Lambda^+_c \to \Xi(1690)^0(\Lambda \bar{K} ^0) K^+)}{\Gamma(\Lambda^+_c \to \Lambda \bar{K} ^0 K^+)} = 0.33 \pm 0.10 \pm 0.04. Further, an analysis of the subresonant structure for the Λc+→Λπ+π+π−\Lambda^+_c \to \Lambda \pi^+\pi^+\pi^- decay mode is presented.Comment: 14 pages, 6 figures, 3 tables, Submitted to Physics Letter

    Study of the decay asymmetry parameter and CP violation parameter in the Lambdac+ --> Lambda pi+ decay

    Full text link
    Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter alpha(Lambdac) in Lambdac --> Lambda pi decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter : A = [alpha(Lambdac)+alpha(antiLambda_c)]/[alpha(Lambdac)-alpha(antiLambda_c)]. We obtain alpha(Lambdac)=-0.78+-0.16+-0.13 and A = -0.07+-0.19+-0.12 where errors are statistical and systematic.Comment: 18 pages, to be submitted to Phys. Lett. B For a list of the FOCUS collaboration, see http://www-focus.fnal.gov/authors.htm

    Measurement of the B-Meson Inclusive Semileptonic Branching Fraction and Electron-Energy Moments

    Get PDF
    We report a new measurement of the B-meson semileptonic decay momentum spectrum that has been made with a sample of 9.4/fb of electron-positron annihilation data collected with the CLEO II detector at the Y(4S) resonance. Electrons from primary semileptonic decays and secondary charm decays were separated by using charge and angular correlations in Y(4S) events with a high-momentum lepton and an additional electron. We determined the semileptonic branching fraction to be (10.91 +- 0.09 +- 0.24)% from the normalization of the electron-energy spectrum. We also measured the moments of the electron energy spectrum with minimum energies from 0.6 GeV to 1.5 GeV.Comment: 36 pages postscript, als available through http://w4.lns.cornell.edu/public/CLNS/, Submitted to PRD (back-to-back with preceding preprint hep-ex/0403052

    Anti-Search for the Glueball Candidate f_J(2220) in Two-Photon Interactions

    Full text link
    Using 13.3 fb^{-1} of e^+e^- data recorded with the CLEO II and CLEO II.V detector configurations at CESR, we have searched for f_J(2220) decays to K^0_{S} K^0_{S} in untagged two-photon interactions. We report an upper limit on the product of the two-photon partial width and the branching fraction, Gamma_gamma gamma cdot B (f_J(2220) to K^0_{S} K^0_{S}) of less than 1.1 eV at the 95% C.L: systematic uncertainties are included. This dataset is four times larger than that used in the previous CLEO publication.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, Submitted to PRD (R

    Observation of a Narrow Resonance of Mass 2.46 GeV/c^2 Decaying to D_s^*+ pi^0 and Confirmation of the D_sJ^* (2317) State

    Full text link
    Using 13.5 inverse fb of e+e- annihilation data collected with the CLEO II detector we have observed a narrow resonance in the Ds*+pi0 final state, with a mass near 2.46 GeV. The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at 2.32 GeV, the DsJ*(2317)+ that decays to Ds+pi0. Reconstructing the Ds+pi0 and Ds*+pi0 final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, dM(Dspi0)=M(Dspi0)-M(Ds) and dM(Ds*pi0)=M(Ds*pi0)-M(Ds*), both of them at values near 350 MeV. We interpret these peaks as signatures of two distinct states, the DsJ*(2317)+ plus a new state, designated as the DsJ(2463)+. Because of the similar dM values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences = 350.0 +/- 1.2 [stat] +/- 1.0 [syst] MeV for the DsJ*(2317) state, and = 351.2 +/- 1.7 [stat] +/- 1.0 [syst] MeV for the new DsJ(2463)+ state. We have also searched, but find no evidence, for decays of the two states via the channels Ds*+gamma, Ds+gamma, and Ds+pi+pi-. The observations of the two states at 2.32 and 2.46 GeV, in the Ds+pi0 and Ds*+pi0 decay channels respectively, are consistent with their interpretations as (c anti-strange) mesons with orbital angular momentum L=1, and spin-parities of 0+ and 1+.Comment: 16 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, version to be published in Physical Review D; minor modifications and fixes to typographical errors, plus an added section on production properties. The main results are unchanged; they supersede those reported in hep-ex/030501

    Population-based genetic effects for developmental stuttering

    Get PDF
    Despite a lifetime prevalence of at least 5%, developmental stuttering, characterized by prolongations, blocks, and repetitions of speech sounds, remains a largely idiopathic speech disorder. Family, twin, and segregation studies overwhelmingly support a strong genetic influence on stuttering risk; however, its complex mode of inheritance combined with thus-far underpowered genetic studies contribute to the challenge of identifying and reproducing genes implicated in developmental stuttering susceptibility. We conducted a trans-ancestry genome-wide association study (GWAS) and meta-analysis of developmental stuttering in two primary datasets: The International Stuttering Project comprising 1,345 clinically ascertained cases from multiple global sites and 6,759 matched population controls from the biobank at Vanderbilt University Medical Center (VUMC), and 785 self-reported stuttering cases and 7,572 controls ascertained from The National Longitudinal Study of Adolescent to Adult Health (Add Health). Meta-analysis of these genome-wide association studies identified a genome-wide significant (GWS) signal for clinically reported developmental stuttering in the general population: a protective variant in the intronic or genic upstream region of SSUH2 (rs113284510, protective allele frequency = 7.49%, Z = −5.576, p = 2.46 × 10−8) that acts as an expression quantitative trait locus (eQTL) in esophagus-muscularis tissue by reducing its gene expression. In addition, we identified 15 loci reaching suggestive significance (p < 5 × 10−6). This foundational population-based genetic study of a common speech disorder reports the findings of a clinically ascertained study of developmental stuttering and highlights the need for further research

    Measurement of the Charge Asymmetry in B→K∗(892)±π∓B\to K^* (892)^{\pm}\pi^{\mp}

    Full text link
    We report on a search for a CP-violating asymmetry in the charmless hadronic decay B -> K*(892)+- pi-+, using 9.12 fb^-1 of integrated luminosity produced at \sqrt{s}=10.58 GeV and collected with the CLEO detector. We find A_{CP}(B -> K*(892)+- pi-+) = 0.26+0.33-0.34(stat.)+0.10-0.08(syst.), giving an allowed interval of [-0.31,0.78] at the 90% confidence level.Comment: 7 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Study of the q^2-Dependence of B --> pi ell nu and B --> rho(omega)ell nu Decay and Extraction of |V_ub|

    Full text link
    We report on determinations of |Vub| resulting from studies of the branching fraction and q^2 distributions in exclusive semileptonic B decays that proceed via the b->u transition. Our data set consists of the 9.7x10^6 BBbar meson pairs collected at the Y(4S) resonance with the CLEO II detector. We measure B(B0 -> pi- l+ nu) = (1.33 +- 0.18 +- 0.11 +- 0.01 +- 0.07)x10^{-4} and B(B0 -> rho- l+ nu) = (2.17 +- 0.34 +0.47/-0.54 +- 0.41 +- 0.01)x10^{-4}, where the errors are statistical, experimental systematic, systematic due to residual form-factor uncertainties in the signal, and systematic due to residual form-factor uncertainties in the cross-feed modes, respectively. We also find B(B+ -> eta l+ nu) = (0.84 +- 0.31 +- 0.16 +- 0.09)x10^{-4}, consistent with what is expected from the B -> pi l nu mode and quark model symmetries. We extract |Vub| using Light-Cone Sum Rules (LCSR) for 0<= q^2<16 GeV^2 and Lattice QCD (LQCD) for 16 GeV^2 <= q^2 < q^2_max. Combining both intervals yields |Vub| = (3.24 +- 0.22 +- 0.13 +0.55/-0.39 +- 0.09)x10^{-3}$ for pi l nu, and |Vub| = (3.00 +- 0.21 +0.29/-0.35 +0.49/-0.38 +-0.28)x10^{-3} for rho l nu, where the errors are statistical, experimental systematic, theoretical, and signal form-factor shape, respectively. Our combined value from both decay modes is |Vub| = (3.17 +- 0.17 +0.16/-0.17 +0.53/-0.39 +-0.03)x10^{-3}.Comment: 45 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Observation of the Ξc+\Xi_c^+ Charmed Baryon Decays to Σ+K−π+\Sigma^+ K^-\pi^+, Σ+Kˉ∗0\Sigma^+ \bar{K}^{*0}, and ΛK−π+π+\Lambda K^-\pi^+\pi^+

    Full text link
    We have observed two new decay modes of the charmed baryon Ξc+\Xi_c^+ into Σ+K−π+\Sigma^+ K^-\pi^+ and Σ+Kˉ∗0\Sigma^+ \bar{K}^{*0} using data collected with the CLEO II detector. We also present the first measurement of the branching fraction for the previously observed decay mode Ξc+→ΛK−π+π+\Xi_c^+\to\Lambda K^-\pi^+\pi^+. The branching fractions for these three modes relative to Ξc+→Ξ−π+π+\Xi_c^+\to\Xi^-\pi^+\pi^+ are measured to be 1.18±0.26±0.171.18 \pm 0.26 \pm 0.17, 0.92±0.27±0.140.92 \pm 0.27 \pm 0.14, and 0.58±0.16±0.070.58 \pm 0.16 \pm 0.07, respectively.Comment: 12 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN
    • …
    corecore