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CLEO Collaboration

Publications and source records attributed to CLEO Collaboration.

At least 145 records · Page 8Linked to original sources

arXiv2005

Search for CP Violation in D^0--> K_S^0 pi^+pi^-

We report on a search for CP violation in the decay of D0 and D0B to Kshort pi+pi-. The data come from an integrated luminosity of 9.0 1/fb of e+e- collisions at sqrt(s) ~ 10 GeV recorded with the CLEO II.V detector. The resonance substructure of this decay is well described by ten quasi-two-body decay channels (K*-pi+, K*0(1430)-pi+, K*2(1430)-pi+, K*(1680)-pi+, Kshort rho, Kshort omega, Kshort f0(980), Kshort f2(1270), Kshort f0(1370), and the ``wrong sign'' K*+ pi-) plus a small non-resonant component. We observe no evidence for CP violation in the amplitudes and phases that describe the decay D0 to K_S^0 pi+pi-.

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arXiv2005

Improved Measurement of the Form Factors in the Decay Lambda_c^+ --> Lambda e^+ nu_e

Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay Lambda_c^+ -> Lambda e^+ nu_e. By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R = f_2/f_1 = -0.31 +/- 0.05(stat) +/- 0.04(syst), the pole mass, M_{pole} = (2.21 +/- 0.08(stat) +/- 0.14(syst)) GeV/c^2, and the decay asymmetry parameter of the Lambda_c, alpha_{Lambda_c} = -0.86 +/- 0.03(stat) +/- 0.02(syst), for = 0.67 (GeV/c^2)^2. We compare the angular distributions of the Lambda_c^+ and Lambda_c^- and find no evidence for CP-violation: A_{Lambda_c} = (alpha_{Lambda_c^+} + alpha_{Lambda_c^-})/ (alpha_{Lambda_c^+} - alpha_{Lambda_c^-}) = 0.00 +/- 0.03(stat) +/- 0.01(syst) +/- 0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A_{Lambda}, for Lambda -> p pi^-.

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arXiv2004

Measuring cal B(D^+ --> mu^+ nu) and the Pseudoscalar Decay Constant f_D^+

In 60 inverse-pb of data taken on the psi(3770) resonance with the CLEO-c detector, we find 8 D+ -> mu+ nu decay candidates that are mostly signal, containing only 1 estimated background. Using this statistically compelling sample, we measure a value of B(D+ -> mu+ nu) = (3.5 +/- 1.4 +/- 0.6) x10^(-4), and determine fD+=(202 +/- 41 +/-17) MeV.

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arXiv2004

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

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.

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arXiv2004

Search for X(3872) in Untagged gamma gamma Fusion and Initial State Radiation Production with CLEO III

We report on an exclusive search for the X(3872) state in the decay pi+ pi- J/psi, J/psi to l+ l- (l = e, mu) from untagged gamma-gamma fusion and initial state radiation production using a 15.1 fb-1 data sample with the CLEO III detector. By taking advantage of the unique pi+ pi- J/psi decay kinematics, separate measurements for each production process are obtained. No signals are observed and preliminary upper limits have been established as [(2J+1)*Width_gamgam(X(3872))*BR(X(3872) to pi+ pi- J/psi)] < 12.9 eV and [Width_ee(X(3872))*BR(X(3872) to pi+ pi- J/psi)] < 8.0 eV, both at a 90% confidence level.

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arXiv2004

Exclusive Multi-Body Hadronic Decays of the psi(2S)

Using data accumulated with the CLEO detector corresponding to an integrated luminosity of 5.46 1/pb on the peak of the psi(2S) and 20.46 1/pb at E_CM=3.67 GeV, we report preliminary branching fraction measurements for seven new decay modes of the psi(2S) (eta 3pi, eta' 3pi, 2(K+ K-), p pbar K+ K-, Lambda Lambdabar pi+ pi-, Lambda pbar K+, and Lambda pbar K+ pi+ pi-) and more precise measurements of nine previously measured modes (2(pi+pi-), 2(pi+pi-) pi0, omega pi+pi-, K+ K- pi+ pi-, phi pi+ pi-, omega K+ K-, phi K+ K-, p pbar pi+ pi-, and Lambda Lambdabar). We also include a study of omega p pbar and obtain an improved upper limit for phi p pbar. Results are compared, where possible, with the corresponding J/psi branching ratios to test the 12% rule.

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arXiv2004

Measurement of \cal{B}(D^+ --> mu^+ nu) and the Pseudoscalar Decay Constant $f_{D^+}$

In 60 pb-1 of data taken on the psi(3770) resonance with the CLEO-c detector, we find 8 D+ to mu+ nu event candidates that are mostly signal, containing only 1 estimated background. Using this statistically compelling sample, we measure preliminary values of B(D+ to mu+ nu) = (3.5 +- 1.4 +- 0.6)*10^{-4}, and determine f_{D+} =(201+- 41+- 17) MeV.

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arXiv2004

First CLEO-c Results on Exclusive D^0 Semileptonic Decays

Based on a data sample of 60 pb-1 collected at the psi(3770) resonance with the CLEO-c detector at CESR, we present improved measurements of absolute branching fractions for exclusive D0 semileptonic decays into K- e+ nu, pi- e+ nu and K*- e+ nu; and the first observation and absolute branching fraction measurement of D0 to rho- e+ nu.

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arXiv2004

Evidence for B^()_s bar{B}^()_s Production at the Upsilon(5S)

Using data collected by the CLEO III detector at CESR, we started a series of investigations on the Upsilon(5S) resonance decay properties. The data sample used for this analysis consists of 0.42 fb-1 of data taken on the Upsilon(5S) resonance, 6.34 fb-1 of data collected on the Upsilon(4S) and 2.32 fb-1 of data taken in the continuum below the Upsilon(4S). B_s mesons are expected to decay predominantly into D_s meson, while the lighter B mesons decay into D_s only about 10% of the time. We exploit this difference to make a preliminary model dependent estimate of the ratio of B_s(*) anti-B_s(*) to the total b anti-b quark pair production at the Upsilon(5S) energy to be (21 +- 3 +- 9)%.

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arXiv2004

Hadronic Branching Fractions of D^0 and D^+, and sigma(e^+e^- --> D bar{D} at E_{cm} = 3.77 GeV

Using nearly 60 pb-1 of data collected with the CLEO-c detector at the psi_prime resonance, we measure absolute branching fractions for three D0 and two D+ Cabibbo-allowed hadronic decay modes, and the cross section for e+e- to D Dbar at Ecm = 3.77 GeV. We report preliminary measurements of the reference branching fractions, B(D0 to K- pi+) = (3.92\pm 0.08\pm 0.23)% and B(D+ to K- pi+ pi+) = (9.8\pm 0.4\pm 0.8)%, and preliminary measurements of other major branching fractions, B(D0 to K- pi+ pi0) = (14.3\pm 0.3\pm 1.0)%, B(D0 to K- pi+ pi- pi+) = (8.1\pm 0.2\pm 0.9)%, and B(D+ to Ks pi+) = (1.61\pm 0.08\pm 0.15)%. We determine preliminary values of the cross sections, sigma(e+ e- to D0 D0bar) = (3.47\pm 0.07\pm 0.15) nb, sigma(e+ e- to D+ D-) = (2.59\pm 0.11\pm 0.11) nb, and sigma(e+ e- to D Dbar) = (6.06\pm 0.13\pm 0.22) nb. We note that the Monte Carlo simulations used in calculating efficiencies in this analysis included final state radiation. However, the branching fractions used in the Particle Data Group averages do not include this effect. If we had not included final state radiation in our simulations, branching fractions would have been 0.5% to 2% lower.

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arXiv2004

Search for the Lepton-Flavor-Violating Leptonic B Decays B^0 -> μ^\pm τ^\mp and B^0 -> μ^\pm τ^\mp

We have searched a sample of 9.6 million BBbar events for the lepton-flavor-violating leptonic B decays, B^0 -> μ^\pm τ^\mp and B^0 -> e^\pm τ^\mp. The τ-lepton was detected through the decay modes τ-> \ellν\barν, where \ell = e, μ. There is no indication of a signal, and we obtain the 90% confidence level upper limits [Br(B^0 -> μ^\pm τ^\mp)] < 3.8 X 10^-5 and [Br(B^0 -> e^\pm τ^\mp)] < 1.1 X 10^-4.

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arXiv2004

Wess-Zumino Current and the Structure of the Decay tau^- to K^-K^+ pi^- nu_tau

We present the first study of the vector (Wess-Zumino) current in tau^-\to K^-pi^-K^+ν_τdecay using data collected with the CLEO III detector at the Cornell Electron Storage Ring. We determine the quantitative contributions to the decay width from the vector and axial vector currents. Within the framework of a model by Kuhn and Mirkes, we identify the quantitative contributions to the total decay rate from the intermediate states ωπ, ρ^{(\prime)}πand K^{*}K.

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arXiv2004

First Observation of a Upsilon(1D) State

We present the first evidence for the production of Upsilon(1D) states in the four-photon cascade, Upsilon(3S)-->gamma chib(2P), chib(2P)-->gamma Upsilon(1D), Upsilon(1D)-->gamma chib(1P), chib(1P)-->gamma Upsilon(1S), followed by the Upsilon(1S) annihilation into e+e- or mu+mu-. The signal has a significance of 10.2 standard deviations. The measured product branching ratio for these five decays, (2.5+-0.5+-0.5)x10^(-5), is consistent with the theoretical estimates. The data are dominated by the production of one Upsilon(1D) state consistent with the J=2 assignment. Its mass is determined to be (10161.1+-0.6+-1.6) MeV, which is consistent with the predictions from potential models and lattice QCD calculations. We also searched for Upsilon(3S)-->gammachib(2P), chib(2P)-->gammaUpsilon(1D), followed by either Upsilon(1D)-->eta Upsilon(1S) or Upsilon(1D)-->pi+pi- Upsilon(1S). We find no evidence for such decays and set upper limits on the product branching ratios.

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arXiv2004

Moments of the B Meson Inclusive Semileptonic Decay Rate using Neutrino Reconstruction

We present a measurement of the composition of B meson inclusive semileptonic decays using 9.4 fb^-1 of e^+e^- data taken with the CLEO detector at the Upsilon(4S) resonance. In addition to measuring the charged lepton kinematics, the neutrino four-vector is inferred using the hermiticity of the detector. We perform a maximum likelihood fit over the full three-dimensional differential decay distribution for the fractional contributions from the B -> X_c l nu processes with X_c = D, D*, D**, and nonresonant X_c, and the process B -> X_u l nu. From the fit results we extract the first and second moments of the M_X^2 and q^2 distributions with minimum lepton-energy requirements of 1.0 GeV and 1.5 GeV. We find = 0.456 +- 0.014 +- 0.045 +- 0.109 (GeV/c^2)^2 with a minimum lepton energy of 1.0 GeV and = 0.293 +- 0.012 +- 0.033 +- 0.048 (GeV/c^2)^2 with minimum lepton energy of 1.5 GeV. The uncertainties are from statistics, detector systematic effects, and model dependence, respectively. As a test of the HQET and OPE calculations, the results for the M^X_c moment as a function of the minimum lepton energy requirement are compared to the predictions.

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arXiv2004

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

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.

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arXiv2004

Measurement of the Decay Rate of Xi_c^0 --> pK^-K^-pi^+ Relative to Xi_c^0 --> Xi^-pi^+

Using the CLEOIII detector at CESR, we have measured the branching ratio of the decay Xic0 to pK-K-pi+ relative to Xic0 to Xi- pi+. We find B(Xic0 to pK-K-pi+)/B(Xic0 to Xi-pi+)= 0.35+/-$0.08(stat)+/-0.05(syst). In the resonant substructure of this mode, we find evidence for Xi_c0 decays to p K*(890)K-, and measure B(Xic0 to p K*(890) K^-).B(K*(890) to K-pi+) /B(Xic0 to Xi-pi+)=0.14+/-0.04(stat)+/-0.02(syst) and B(Xic0 to pK-K-pi+)/B(Xic0 to Xi-pi+)=0.21+/-0.05(stat)+/-0.03(syst) for the non-resonant Xic0 decays pK-K-pi+ decays.

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arXiv2003

Observation of the Hadronic Transitions chi_b1,2 (2P) --> omega Upsilon(1S)

The CLEO Collaboration has made the first observations of hadronic transitions among bottomonium (b-bbar) states other than the dipion transitions among upsns states. In our study of Y(3S) decays, we find a significant signal for Y(3S) -> gamma omega Y(1S) that is consistent with radiative decays Y(3S) -> gamma chi_b1,2(2P), followed by chi_b1,2(2P) -> omega Y(1S). The branching ratios we obtain are B(chi_b1(2P) -> omega Y(1S)) = (1.63 +0.35-0.31 +0.16-0.15)% and B(chi_b2(2P) -> omega Y(1S)) = (1.10 +0.32-0.28 +0.11-0.10)%, in which the first error is statistical and the second is systematic.

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arXiv2003

Dalitz Analysis of D^0 --> K_S^0 pi+ pi-

In e^+e^- collisions using the CLEO detector we have studied the decay of the D^0 to the final state K_S^0 pi^+ pi^- with the initial flavor of the D^0 tagged in charged D^* decay. We use the Dalitz technique to measure the resonant substructure in this final state and clearly observe ten different contributions by fitting for their amplitudes and relative phases. We observe a K^{* +} pi^- component which arises from doubly Cabibbo suppressed decays or D^0 - {D^0}-bar mixing.

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