arXiv subjects

CLEO Collaboration

Publications and source records attributed to CLEO Collaboration.

At least 55 records · Page 3Linked to original sources

arXiv2008

Observation of chi-b(1PJ,2PJ) decays to light hadrons

Analyzing $Υ(nS)$ decays acquired with the CLEO detector operating at the CESR $e^+e^-$ collider, we measure for the first time the product branching fractions ${\cal B}[Υ(nS)\toγχ_{b}((n-1)P_J)] \times {\cal B}[χ_{b}(n-1)P_J)\to X_i]$ for $n=2$ and 3, where $X_i$ denotes, for each $i$, one of the fourteen exclusive light-hadron final states for which we observe significant signals in both $χ_b(1P_J)$ and $χ_b(2P_J)$ decays. We also determine upper limits for the electric dipole (E1) transitions $Υ(3S) \to γχ_b(1P_J)$.

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arXiv2008

Search for Lepton Flavor Violation in Upsilon Decays

In this Letter we describe a search for lepton flavor violation (LFV) in the bottomonium system. We search for leptonic decays of Upsilon(nS)(n=1,2, and 3) into muon and tau using the data collected with the CLEO III detector. We identify the tau lepton using its leptonic decay into electron and utilize multidimensional likelihood fitting with PDF shapes measured from independent data samples. We report our estimates of 95% CL upper limits on LFV branching fractions of Upsilon mesons. We interpret our results in terms of the exclusion plot for the energy scale of a hypothetical new interaction versus its effective LFV coupling in the framework of effective field theory.

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arXiv2008

Precision Measurement of B(D+ -> mu+ nu) and the Pseudoscalar Decay Constant fD+

We measure the branching ratio of the purely leptonic decay of the D+ meson with unprecedented precision as B(D+ -> mu+ nu) = (3.82 +/- 0.32 +/- 0.09)x10^(-4), using 818/pb of data taken on the psi(3770) resonance with the CLEO-c detector at the CESR collider. We use this determination to derive a value for the pseudoscalar decay constant fD+, combining with measurements of the D+ lifetime and assuming |Vcd| = |Vus|. We find fD+ = (205.8 +/- 8.5 +/- 2.5) MeV. The decay rate asymmetry [B(D+ -> mu+ nu)-B(D- -> mu- nu)]/[B(D+ -> mu+ nu)+B(D- -> mu- nu)] = 0.08 +/- 0.08, consistent with no CP violation. We also set 90% confidence level upper limits on B(D+ -> tau+ nu) < 1.2x10^(-3) and B(D+ -> e+ nu) < 8.8x10^(-6).

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arXiv2008

Branching Fractions for Transitions of psi(2S) to J/psi

We report determination of branching fractions for the decays psi(2S) --> h + J/psi, where h=any, pi+pi-, pi0pi0, eta, pi0, and gamma gamma through chi_{c0,1,2}. These measurements use 27M psi(2S) decays produced in e+e- collision data collected with the CLEO detector. The resulting branching fractions and ratios thereof improve upon previously achieved precision in all cases, and in combination with other measurements permit determination of B(chi_cJ --> gamma J/psi) and B(psi(2S) --> light hadrons).

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arXiv2008

Search for Light CP-odd Higgs in Radiative Decays of Upsilon(1S)

We search for a non-SM-like CP-odd Higgs boson (a0_1) with m(a0_1)< 2m(b) in radiative decays of the Upsilon(1S), using 21.5M Upsilon(1S) mesons directly produced in e+e- annihilation. We investigate a0_1 --> tau+tau- and a0_1 --> mu+mu- decay channels. No significant signal is found. We obtain upper limits on the product of B(Upsilon(1S)-->gamma a0_1) and B(a0_1-->tau+tau-) or B(a0_1-->mu+mu-). Our tau+tau- results are almost two orders of magnitude more stringent than previous upper limits. Our data provide no evidence for a Higgs state with a mass of 214 MeV decaying to mu+mu-. Existence of such a state was previously proposed as an explanation for 3 Sigma+ --> p mu+mu- events, having mu+mu- masses just above the kinematic threshold, observed by the HyperCP experiment. Our results constrain NMSSM models.

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arXiv2008

Flavour physics at CLEO-c

Three CLEO-c results related to flavour-physics are presented: the determination of the strong-phase difference between D0->K+pi- and D0->K-pi+, delta, the measurement of the coherence parameter and average strong-phase difference between D0->K+pi-pi-pi+ and D0 -> K-pi+pi+pi- and measurements of the variation of strong-phase difference between D0 and D0bar decays to K0Spi+pi- over phase space. All measurements are important for determining the unitarity triangle angle gamma from B->D(*)K(*) decays. Furthermore, the measurement of delta is important for interpreting D0-D0bar mixing.

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arXiv2008

The measurement of R at CLEO

Measurements of the total cross section of e+e- -> hadrons are presented in two different ranges of centre-of-mass energy. The measurements are made using the CLEO III and CLEO-c detectors at the Cornell Electron Storage Ring. The absolute cross sections and the values of R, the ratio of hadronic to muon pair production cross sections, are determined at seven centre-of-mass energies between 6.964 and 10.538 GeV. The total cross sections and values of R are also determined at thirteen centre-of-mass energies between 3.97 and 4.26 GeV; in addition, the inclusive and exclusive cross sections for D+, D0 and Ds+ production are presented. Furthermore, for the lower centre-of-mass energy range, exclusive cross-sections are presented for final states consisting of two charm mesons: DDbar, D*Dbar, DDbar*, D*Dbar*, Ds+Ds-, Ds*+Ds-, Ds+Ds*-, DDbar*pi and D*Dbar*pi.

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arXiv2008

Exclusive Baryon-Antibaryon Decays of the chi_cJ Mesons

Using a sample of 2.59 \times 10^7 psi(2S) decays collected by the CLEO--c detector, we present results of a study of chi_{cJ} (J=0,1,2) decays into baryon-antibaryon final states. We present the world's most precise measurements of the chi_cJ -> p-pbar and chi_cJ -> Lambda-Lambdabar branching fractions, and the first measurements of chi_c0 decays to other hyperons. These results illuminate the decay mechanism of the chi_c states.

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arXiv2008

Observation of J/psi --> 3 gamma

We report the first observation of the decay J/psi --> 3 gamma. The signal has a statistical significance of 6 sigma and corresponds to a branching fraction of B(J/psi --> 3 gamma) = (1.2 +- 0.3 +- 0.2) x 10^-5, in which the errors are statistical and systematic, respectively. The measurement uses psi(2S) --> pi+ pi- J/psi events acquired with the CLEO-c detector operating at the CESR e+e- collider.

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arXiv2008

Absolute Branching Fractions of Cabibbo-Suppressed D --> K Kbar Decays

Using 281/pb of data collected with the CLEO-c detector at the psi(3770) resonance, we have studied Cabibbo-suppressed decays of D mesons to final states with two kaons. We present results for the absolute branching fractions of the modes D^0 --> K^+ K^-, D^0 --> K^0_S K^0_S, and D^+ --> K^+ K^0_S. We measure B(D^0 --> K^+ K^-) = (4.08 +- 0.08 +- 0.09) x 10^-3, B(D^0 --> K^0_S K^0_S) = (1.46 +- 0.32 +- 0.09) x 10^-4, and B(D^+ --> K^+ K^0_S) = (3.14 +- 0.09 +- 0.08) x 10^-3. We also determine the ratio B(D^0 --> K^+ K^-)/B(D^0 --> pi^+ pi^-) = 2.89 +- 0.05 +- 0.06. For each measurement, the first uncertainty is statistical and the second uncertainty is systematic.

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arXiv2008

Precision Measurement of the Mass of the h_c(1P1) State of Charmonium

A precision measurement of the mass of the h_c(1P1) state of charmonium has been made using a sample of 24.5 million psi(2S) events produced in e+e- annihilation at CESR. The reaction used was psi(2S) -> pi0 h_c, pi0 -> gamma gamma, h_c -> gamma eta_c, and the reaction products were detected in the CLEO-c detector. Data have been analyzed both for the inclusive reaction and for the exclusive reactions in which eta_c decays are reconstructed in fifteen hadronic decay channels. Consistent results are obtained in the two analyses. The averaged results of the present measurements are M(h_c)=3525.28+-0.19 (stat)+-0.12(syst) MeV, and B(psi(2S) -> pi0 h_c)xB(h_c -> gamma eta_c)= (4.19+-0.32+-0.45)x10^-4. Using the 3PJ centroid mass, Delta M_hf(1P)= - M(h_c) = +0.02+-0.19+-0.13 MeV.

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arXiv2008

Measurement of exclusive D meson decays to eta and eta' final states and SU(3) amplitude analysis

Using 281 pb^-1 of data collected with the CLEO-c detector, we present new measurements of Cabibbo-suppressed decays of D0 and D+ mesons to eta and eta' final states. We make first observations of D0-->eta'pi0, eta eta, eta eta', and eta pi+ pi-, and find evidence for D+ --> eta pi+ pi0$, D+ --> eta' pi+ pi0 and D0 --> eta' pi+ pi-. We also report on improved measurements of D0-->eta pi0, D+ --> eta pi+ and D+ --> etap' pi+. Using the measured two-body Cabibbo-suppressed decays, we extract amplitudes for specific flavor topologies and compare them to those from Cabibbo-favored decays.

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arXiv2008

First Observation of the Decay D_s^+ to proton anti-neutron

Using e^+e^- -> D_s^*+ D_s^- data collected near the peak D_s production energy, E_cm=4170 MeV, with the CLEO-c detector, we present the first observation of the decay D_s^+ -> proton anti-neutron. We measure a branching fraction B(D_s^+ -> p anti-n = (1.30 +- 0.36 +0.12 -0.16) x 10^-3. This is the first observation of a charmed meson decaying into a baryon-antibaryon final state.

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arXiv2008

Absolute Measurement of Hadronic Branching Fractions of the D_s^+ Meson

The branching fractions of D_s meson decays serve to normalize many measurements of processes involving charm quarks. Using 298 /pb of e+ e- collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight D_s decays with a double tag technique. In particular we determine the branching fraction B(D_s -> K- K+ pi+) = (5.50 +- 0.23 +- 0.16)%, where the uncertainties are statistical and systematic respectively. We also provide partial branching fractions for kinematic subsets of the K- K+ pi+ decay mode.

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arXiv2008

Measurement of the Absolute Branching Fraction of D_s^+ --> tau^+ nu_tau Decay

Using a sample of tagged D_s decays collected near the D^*_s D_s peak production energy in e+e- collisions with the CLEO-c detector, we study the leptonic decay D^+_s to tau^+ nu_tau via the decay channel tau^+ to e^+ nu_e bar{nu}_tau. We measure B(D^+_s to tau^+ nu_tau) = (6.17 +- 0.71 +- 0.34) %, where the first error is statistical and the second systematic. Combining this result with our measurements of D^+_s to mu^+ nu_mu and D^+_s to tau^+ nu_tau (via tau^+ to pi^+ bar{nu}_tau), we determine f_{D_s} = (274 +- 10 +- 5) MeV.

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arXiv2008

Two-Photon Widths of the chi_cJ States of Charmonium

Using a data sample of 24.5 million psi(2S) the reactions psi(2S)->gamma chi_cJ, chi_cJ->gamma gamma have been studied for the first time to determine the two-photon widths of the chi_cJ states of charmonium in their decay into two photons. The measured quantities are B(psi(2S)->gamma chi_c0)xB(chi_c0->gamma gamma)=(2.22+-0.32+-0.10)x10^-5, and B(psi(2S)->gamma chi_c2)xB(chi_c2->gamma gamma)=(2.70+-0.28+-0.15)x10^-5. Using values for B(psi(2S)->gamma chi_c0,c2) and Γ(chi_c0,c2) from the literature the two-photon widths are derived to be Γ_{gamma gamma}(chi_c0)=(2.53+-0.37+-0.26) keV, Γ_{gamma gamma}(chi_c2)=(0.60+-0.06+-0.06) keV, and R=Γ_{gamma gamma}(chi_c2)/Γ_{gamma gamma}(chi_c0)= 0.237+-0.043+-0.034. The importance of the measurement of R is emphasized. For the forbidden transition, chi_c1->gamma gamma, an upper limit of Γ_{gamma gamma}(chi_c1)<0.03 keV is established.

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arXiv2008

Measurement of Charm Production Cross Sections in e+e- Annihilation at Energies between 3.97 and 4.26 GeV

Using the CLEO-c detector at the Cornell Electron Storage Ring, we have measured inclusive and exclusive cross sections for the production of D+, D0 and Ds+ mesons in e+e- annihilations at thirteen center-of-mass energies between 3.97 and 4.26 GeV. Exclusive cross sections are presented for final states consisting of two charm mesons (DD, D*D, D*D*, Ds+Ds-, Ds*+Ds-, and Ds*+Ds*-) and for processes in which the charm-meson pair is accompanied by a pion. No enhancement in any final state is observed at the energy of the Y(4260).

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arXiv2007

A Study of the Semileptonic Charm Decays D^0 --> pi^- e^+ nu_e, D^+ --> pi^0 e^+ nu_e, D^0 --> K^- e^+ nu_e, and D^+ --> barK^0 e^+ nu_e

Using a sample of 1.8 million DDbar meson pairs collected at the psi(3770) with the CLEO-c detector, we study the semileptonic decays D^0 -> pi^- e^+ nu_e, D^+ -> pi^0 e^+ ν_e, D^0 -> K^- e^+ ν_e, and D^+ -> Kbar^0 e^+ nu_e. For the total branching fractions we find B(D^0 -> pi^- e^+ ν_e) = 0.299(11)(9)%, B(D^+ -> pi^0 e^+ ν_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+ nu_e) = 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%, where the first error is statistical and the second systematic. In addition, form factors are studied through fits to the partial branching fractions obtained in five q^2 ranges. By combining our results with recent unquenched lattice calculations, we obtain |Vcd| = 0.217(9)(4)(23) and |Vcs| = 1.015(10)(11)(106), where the final error is theoretical.

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