562 research outputs found

    Measurement of Interfering K^*+K^- and K^*-K^+ Amplitudes in the Decay D^0 --> K^+K^-pi^0

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    We have studied the Cabibbo-suppressed decay mode D^0 into K^+ K^- pi^0 using a Dalitz plot technique and find the strong phase difference delta_D [defined as delta_(K*^- K^+) - delta_(K*^+ K^-)] = 332 degrees +- 8 degrees +- 11 degrees and relative amplitude r_D [defined as a_(K*^- K^+) / a_(K*^+ K^-)] = 0.52 +- 0.05 +- 0.04. This measurement indicates significant destructive interference between D^0 into K^+ (K^- pi^0)_K*^- and D^0 into K^- (K^+ pi^0)_K*^+ in the Dalitz plot region where these two modes overlap. This analysis uses 9.0 fb^(-1) of data collected at s^(1/2) of approximately 10.58 GeV with the CLEO III detector.Comment: 10 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to Phys. Rev. D (Rapid Communications

    Update of the measurement of the cross section for e^+e^- -> psi(3770) -> hadrons

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    We have updated our measurement of the cross section for e^+e^- -> psi(3770) -> hadrons, our publication "Measurement of sigma(e^+e^- -> psi(3770) -> hadrons) at E_{c.m.} = 3773 MeV", arXiv:hep-ex/0512038, Phys.Rev.Lett.96, 092002 (2006). Simultaneous with this arXiv update, we have published an erratum in Phys.Rev.Lett.104, 159901 (2010). There, and in this update, we have corrected a mistake in the computation of the error on the difference of the cross sections for e^+e^- -> psi(3770) -> hadrons and e^+e^- -> psi(3770) -> DDbar. We have also used a more recent CLEO measurement of cross section for e^+e^- -> psi(3770) -> DDbar. From this, we obtain an upper limit on the branching fraction for psi(3770) -> non-DDbar of 9% at 90% confidence level.Comment: 3 pages, 0 figures. This is an erratum to Phys.Rev.Lett.96:092002,2006. Added a reference

    Measurement of the Decay Constant fDS+f_D{_S^+} using $D_S^+ --> ell^+ nu

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    We measure the decay constant fDs using the Ds -> l+ nu channel, where the l+ designates either a mu+ or a tau+, when the tau+ -> pi+ nu. Using both measurements we find fDs = 274 +-13 +- 7 MeV. Combining with our previous determination of fD+, we compute the ratio fDs/fD+ = 1.23 +- 0.11 +- 0.04. We compare with theoretical estimates.Comment: 6 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2007

    Search for Radiative Decays of Upsilon(1S) into eta and eta'

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    We report on a search for the radiative decay of Upsilon(1S) to the pseudoscalar mesons eta and etaprime in 21.2 +/- 0.2 times 10^6 Upsilon(1S) decays collected with the CLEO III detector at the Cornell Electron Storage Ring (CESR). The eta meson was reconstructed in the three modes eta to gamma-gamma, eta to pi+pi-pi0 and eta to 3pi0. The etaprime meson was reconstructed in the mode etaprime to pi+ pi- eta with eta decaying through any of the above three modes, and also etaprime to gamma rho, where rho decays to pi^+ pi^-. Five out of the seven sub-modes are found to be virtually background-free. In four of them we find no signal candidates and in one Upsilon(1S) to gamma-etaprime, etaprime to pi+ pi- eta, eta to pi+pi-pi0 there are two good signal candidates, which is insufficient evidence to claim a signal. The other two sub-modes eta to gamma-gamma and etaprime to gamma rho are background limited, and show no excess of events in their signal regions. We combine the results from different channels and obtain upper limits at the 90% C.L. which are B(Upsilon(1S) to gamma eta) < 1.0 times 10^-6 and B(Upsilon(1S) to gamma etaprime) < 1.9 times 10^-6. Our limits are an order of magnitude tighter than the previous ones and below the predictions made by some theoretical models.Comment: 14 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2007/, Submitted to PR

    Absolute Branching Fraction Measurements for D^+ and D^0 Inclusive Semileptonic Decays

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    We present measurements of the inclusive branching fractions for the decays D^+ -> X e^+ nu_e and D^0 -> X e^+ nu_e, using 281 pb^-1 of data collected on the psi(3770) resonance with the CLEO-c detector. We find Br(D^0 ->Xe^+\nu_e) = (6.46 \pm 0.17 \pm 0.13)% and Br((D^+ -> Xe^+nu_e) = (16.13 \pm 0.20 \pm 0.33)%. Using the known D meson lifetimes, we obtain the ratio Gamma{D^+}^sl/Gamma_{D^0}^sl= 0.985\pm 0.028\pm 0.015, confirming isospin invariance at the level of 3%. The positron momentum spectra from D^+ and D^0 have consistent shapes.Comment: 6 pages postscript,also available through this http://www.lns.cornell.edu/public/CLNS/2006

    New Measurements of Upsilon(1S) Decays to Charmonium Final States

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    Using substantially larger data samples collected by the CLEO III detector, we report on new measurements of the decays of Upsilon(1S) to charmonium final states, including J/Psi, psi(2S), and chi_cJ. The latter two are first observations of these decays. We measure the branching fractions as follows: B(Y(1S)--> J/Psi+X)=(6.4+-0.4+-0.6)x10^-4, B(Y(1S)--> psi(2S)+X)/B(Y(1S)--> J/Psi+X)=0.41+-0.11+-0.08, B(Y(1S)--> chi_c1+X)/B(Y(1S)--> J/Psi+X)=0.35+-0.08+-0.06, B(Y(1S)--> chi_c2+X)/B(Y(1S)--> J/Psi+X)=0.52+-0.12+-0.09, and B(Y(1S)--> chi_c0+X)/B(Y(1S)--> J/Psi+X)<7.4% at 90% confidence level. We also report on the momentum and angular spectra of J/Psi's in Upsilon(1S) decay. The results are compared to predictions of the color octet and color singlet models.Comment: 27 pages postscript,also available through http://w4.lns.cornell.edu/public/CLNS/, submitted to PR

    Confirmation of the Y(4260) Resonance Production in ISR

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    Using 13.3 fb^-1 of e+e- collision data taken in the Upsilon(1S-4S) region with the CLEO III detector at the CESR collider, a search has been made for the new resonance Y(4260) recently reported by the BaBar Collaboration. The production of Y(4260) in initial state radiation (ISR), and its decay into pi+pi-J/psi are confirmed. A good quality fit to our data is obtained with a single resonance. We determine M(Y(4260))=(4284+17-16(stat)+-4(syst)) MeV/c^2, Gamma(Y(4260))=(73+39-25(stat)+-5(syst)) MeV/c^2, and Gamma_ee(Y(4260))xBr(Y(4260)->pi+pi-J/psi)=(8.9+3.9-3.1(stat)+-1.9(syst)) eV/c^2.Comment: 8 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to PRD (Rapid Comm.

    A Study of Exclusive Charmless Semileptonic B Decays and Extraction of |V_{ub}| at CLEO

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    We have studied semileptonic B decay to the exclusive charmless states pi, rho/omega, eta and eta' using the full 15.5 fb^-1 CLEO Upsilon(4S) sample, with measurements performed in subregions of phase space to minimize dependence on a priori knowledge of the form factors involved. We find total branching fractions B(B^0 -> pi^-l^+nu) = (1.37 +- 0.15_stat +- 0.11_sys) x 10^-4 and B(B^0 -> rho^- l^+ nu) = (2.93 +- 0.37_stat +- 0.37_sys) x 10^-4. We find evidence for B^+ -> eta' l^+ nu, with B(B^+ -> eta' l^+ nu) = (2.66 +- 0.80_stat +- 0.56_sys) x 10^-4 and 1.20 x 10^-4 eta' l^+ nu) < 4.46 x 10^-4 (90% CL). We also limit B(B^+ -> eta l^+ nu) < 1.01 x 10^-4 (90% CL). By combining our B -> pi l nu information with unquenched lattice calculations, we find |V_ub| = (3.6 +- 0.4 +- 0.2 +0.6 -0.4) x 10^-3, where the errors are statistical, experimental systematic, and theoretical systematic, respectively.Comment: 35 pages, 15 figures; revise
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