arXiv subjects

CLEO Collaboration

Publications and source records attributed to CLEO Collaboration.

At least 37 records · Page 2Linked to original sources

arXiv2009

Study of D0 --> pi- e+ nu(e), D+ --> pi0 e+ nu(e), D0 --> K- e+ nu(e), and D+ --> anti-K0 e+ nu(e) in Tagged Decays of the psi(3770) Resonance

Using psi(3770) --> DDbar events collected with the CLEO-c detector at the Cornell e+ e- storage ring, tagged by fully reconstructing one D meson in a hadronic decay mode, we measure absolute branching fractions and differential decay rates for D0 --> pi- e+ nu(e), D+ --> pi0 e+ nu(e), D0 --> K- e+ nu(e), and D+ --> anti-K0 e+ nu(e). The measured decay rates are used to study semileptonic form factors governing these transitions and to test unquenched Lattice QCD (LQCD) calculations. We average our results with previously published CLEO-c measurements of the same quantities using a neutrino reconstruction technique. Combining LQCD calculations of form factor absolute normalizations f+(0) and measurements of f(pi)+(0)*|Vcd| and f(K)+(0)*|Vcs|, we find |Vcd| = 0.223(8)(3)(23) and |Vcs| = 1.019(10)(7)(106), where the uncertainties are statistical, experimental systematic, and from LQCD, respectively.

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arXiv2009

Observation of D^+ to eta e^+ nu_e

Using a 281 pb^-1 data sample collected at the psi(3770) resonance with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of D^+ to eta e^+ nu_e. We also set upper limits for D^+ to eta' e^+ nu_e and D^+ to phi e^+ nu_e that are about two orders of magnitude more restrictive than those obtained by previous experiments.

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arXiv2009

Evidence for Decays of h_c to Multi-Pion Final States

Using a sample of 2.59 x 10^7$ psi(2S) decays collected by the CLEO--c detector, we present results of a search for the decay chain psi(2S) -> pi^0 h_c, h_c -> n(pi^+ pi^-) pi^0, n=1,2,3. We observe no significant signals for n=1 and n=3 and set upper limits for the corresponding decay rates. First evidence for the decay h_c øpi^+ pi^- pi^+ pi^- pi^0 is presented, and a product branching fraction of B(psi(2S) -> h_c) x B(h_c -> 2(pi^+ pi^-) pi^0)=1.88^{+0.48+0.47}_{-0.45-0.30} x 10^{-5} is measured. This result implies that h_c -> $ hadrons and h_c -> gamma eta_c have comparable rates, in agreement with expectations.

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arXiv2009

Charmonium decays to gamma pi0, gamma eta, and gamma eta'

Using data acquired with the CLEO-c detector at the CESR e+e- collider, we measure branching fractions for J/psi, psi(2S), and psi(3770) decays to gamma pi0, gamma eta, and gamma eta'. Defining R_n = B[ psi(nS)-->gamma eta ]/B[ psi(nS)-->gamma eta' ], we obtain R_1 = (21.1 +- 0.9)% and, unexpectedly, an order of magnitude smaller limit, R_2 < 1.8% at 90% C.L. We also use J/psi-->gamma eta' events to determine branching fractions of improved precision for the five most copious eta' decay modes.

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arXiv2009

Dalitz Analyses in Charm

Dalitz analyses in charm give access to both magnitudes and phases of the charm decay amplitudes. They play a significant role in charm-mixing measurements, in the measurement of the CP-violating phase gamma in B decays to charm, and in the analysis of light meson resonances. We review recent results in all three categories.

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arXiv2009

Inclusive Hadron Yields from Ds+ Decays

We study the inclusive decays of Ds+ mesons, using data collected near the Ds*+ Ds- peak production energy E_cm=4170 MeV by the CLEO-c detector. We report the inclusive yields of Ds+ decays to K^+ X, K^- X, KS0 X, pi^+ X, pi^- X, pi^0 X, eta X, eta' X, phi X, omega X and f0(980) X, and also decays into pairs of kaons, Ds+ -> KK-bar X. Using these measurements, we obtain an overview of Ds+ decays.

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arXiv2009

Measurement of B(Ds+ -->ell+ nu) and the Decay Constant fDs From 600/pb of e+e- Annihilation Data Near 4170 MeV

We examine e+e- --> Ds^-D_s^{*+} and Ds^{*-}Ds^{+} interactions at 4170 MeV using the CLEO-c detector in order to measure the decay constant fDs with good precision. Previously our measurements were substantially higher than the most precise lattice based QCD calculation of (241 +/- 3) MeV. Here we use the D_s^+ --> ell^+ nu channel, where the ell^+ designates either a mu^+ or a tau^+, when the tau^+ --> pi^+ anti-nu. Analyzing both modes independently, we determine B(D_s^+ --> mu^+ nu)= 0.565 +/- 0.045 +/- 0.017)%, and B(D_s^+ --> mu^+ nu)= (6.42 +/- 0.81 +/- 0.18)%. We also analyze them simultaneously to find an effective value of B^{eff}(D_s^+ --> mu^+ nu)= (0.591 +/- 0.037 +/- 0.018)% and fDs=(263.3 +/- 8.2 +/- 3.9) MeV. Combining with the CLEO-c value determined independently using D_s^+ --> tau^+ nu, tau^+ --> e^+ nu anti-nu decays, we extract fDs=(259.5 +/- 6.6 +/- 3.1) MeV. Combining with our previous determination of B(D^+ --> mu^+ nu), we extract the ratio fDs/fD+=1.26 +/- 0.06 +/- 0.02. No evidence is found for a CP asymmetry between Gamma(D_s^+ --> mu^+ν) and Γ(D_s^- --> mu^- nu); specifically the fractional difference in rates is measured to be (4.8 +/- 6.1)%. Finally, we find B(D_s^+ --> e^+ nu) < 1.2x10^{-4} at 90% confidence level.

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arXiv2009

Improved Measurement of Absolute Branching Fraction of Ds to tau nu

We have studied the leptonic decay D^+_s to tau^+ nu_tau, via the decay channel tau^+ to e^+ nu_e anti-nu_tau, 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 obtain B(D^+_s to tau^+ nu_tau) = (5.30 +- 0.47 +- 0.22) % and determine the decay constant f_Ds = (252.5 +- 11.1 +- 5.2) MeV, where the first uncertainties are statistical and the second are systematic.

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arXiv2009

Observation of $η'$ decays to $π^+π^-π^0$ and $π^+π^-\e^+e^-$

Using psi(2S) --> pi+ pi- J/psi, J/psi --> gamma eta' events acquired with the CLEO-c detector at the CESR e+e- collider, we make the first observations of the decays eta' --> pi+ pi- pi0 and eta' --> pi+ pi- e+ e-, measuring absolute branching fractions (37 +11 -9 +- 4) x 10^-4 and (25 +12 -9 +- 5) x 10^-4, respectively. For eta' --> pi+ pi- pi0, this result probes the mechanism of isospin violation and the roles of pi0/eta/eta'-mixing and final state rescattering in strong decays. We also set upper limits on branching fractions for eta' decays to pi+ pi- mu+ mu-, 2(pi+ pi-), pi+ pi- 2pi0, 2(pi+ pi-)pi0, 3(pi+ pi-), and invisible final states.

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arXiv2009

Improved Measurement of Branching Fractions for pipi Transitions among Upsilon(nS)States

Using samples of (5.93 +/- 0.10) x 10^6 Upsilon(3S) decays and (9.11 +/- 0.14) x 10^6 Upsilon(2S) decays collected with the CLEO detector, we report improved measurements of the branching fractions for the following five transitions: B(Upsilon(3S)-->Upsilon(1S) pi^+ pi^-) = (4.46 +/- 0.01 +/- 0.13)%, B(Upsilon(2S)-->Upsilon(1S) pi^+ pi^-) = (18.02 +/- 0.02 +/- 0.61)%, B(Upsilon(3S)-->Upsilon(1S) pi^0 pi^0) = (2.24 +/- 0.09 +/- 0.11)%, B(Upsilon(2S)-->Upsilon(1S) pi^0 pi^0) = (8.43 +/- 0.16 +/- 0.42)% and B(Upsilon(3S)-->Upsilon(2S) pi^0 pi^0) = (1.82 +/- 0.09 +/- 0.12)%. In each case the first uncertainty reported is statistical, while the second is systematic.

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arXiv2009

J/psi and psi(2S) Radiative Transitions to eta_c

Using 24.5 million psi(2S) decays collected with the CLEO-c detector at CESR we present the most precise measurements of magnetic dipole transitions in the charmonium system. We measure B(psi(2S)->gamma eta_c) = (4.32+/-0.16+/-0.60)x10^-3, B(J/psi->gamma eta_c)/B(psi(2S)->gamma eta_c) = 4.59+/-0.23+/-0.64, and B(J/psi->gamma eta_c) = (1.98+/-0.09+/-0.30)%. We observe a distortion in the eta_c line shape due to the photon-energy dependence of the magnetic dipole transition rate. We find that measurements of the eta_c mass are sensitive to the line shape, suggesting an explanation for the discrepancy between measurements of the eta_c mass in radiative transitions and other production mechanisms.

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arXiv2008

Inclusive chi_bJ(nP) Decays to D0 X

Using Upsilon(2S) and Upsilon(3S) data collected with the CLEO III detector we have searched for decays of chi_bJ to final states with open charm. We fully reconstruct D0 mesons with p_D0 > 2.5 GeV/c in three decay modes (K-pi+, K-pi+pi0, and K-pi-pi+pi+) in coincidence with radiative transition photons that tag the production of one of the chi_bJ(nP) states. We obtain significant signals for the two J=1 states. Recent NRQCD calculations of chi_{bJ}(nP) --> c cbar X depend on one non-perturbative parameter per chi_bJ triplet. The extrapolation from the observed D0 X rate over a limited momentum range to a full c cbar X rate also depends on these same parameters. Using our data to fit for these parameters, we extract results which agree well with NRQCD predictions, confirming the expectation that charm production is largest for the J=1 states. In particular, for J=1, our results are consistent with c cbar g accounting for about one-quarter of all hadronic decays.

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arXiv2008

Observation of Upsilon(2S) -> eta Upsilon(1S) and search for related transitions

We report the first observation of the transition Upsilon(2S) > eta Upsilon(1S), with branching fraction B=(2.1+0.7-0.6(stat.)+-0.3(syst.)) x 10^{-4} and statistical significance 5.3 sigma. Data were acquired with the CLEO detector at the CESR e+ e- symmetric collider. This is the first process observed involving a b-quark spin flip. Upper limits at 90% confidence level for related processes, in units of 10^{-4}, are B[Upsilon(2S) -> pi0 Upsilon(1S)] < 1.8, B[Upsilon(3S) -> eta Upsilon(1S)] < 1.8, B[Upsilon(3S) -> pi0 Upsilon(1S)] < 0.7, and B[Upsilon(3S) -> pi0 Upsilon(2S)] < 5.1.

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arXiv2008

New Measurement of Exclusive Decays of the chi_c0 and chi_c2 to Two-Meson Final States

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_{c0} and chi_{c2} decays into two-meson final states. We present the world's most precise measurements of the chi_{cJ,(J=0,2)} -> pi^+pi^-, pi^0 pi^0, K^+K^-, K^0_S K^0_S, eta eta and eta^{prime} eta^{prime} branching fractions, and a search for chi_c decays into eta eta^{prime}. These results shed light on the mechanism of charmonium decays into pseudoscalar mesons.

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arXiv2008

Measurement of the eta'-meson mass using J/psi--> gamma eta'

We measure the mass of the eta' meson using psi(2S)--> pi+ pi- J/psi, J/psi--> gamma eta' events acquired with the CLEO-c detector operating at the CESR e+e- collider. Using three decay modes, eta'--> rho0 gamma, eta'--> pi+ pi- eta with eta--> gamma gamma, and eta'--> pi+ pi- eta with eta--> pi+ pi- pi0, we find M(eta') = 957.793 +- 0.054 +- 0.036 MeV, in which the first uncertainty is statistical and the second is systematic. This result is consistent with but substantially more precise than the current world average.

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arXiv2008

Search for CP Violation in the Dalitz-Plot Analysis of D+/- -> K+ K- pi+/-

We report on a search for CP asymmetry in the singly Cabibbo-suppressed decay D+ -> K+ K- pi+ using a data sample of 818 pb-1 accumulated with the CLEO-c detector on the psi(3770) resonance. A Dalitz-plot analysis is used to determine the amplitudes of the intermediate states. We find no evidence for CP violation either in specific two-body amplitudes or integrated over the entire phase space. The CP asymmetry in the latter case is measured to be (-0.03+-0.84+-0.29)%.

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arXiv2008

Observation of chi_cJ radiative decays to light vector mesons

Using a total of 2.74 x 10^7 decays of the psi(2S) collected with the CLEO-c detector, we present a study of chi_cJ -> gamma V, where V = rho^0, omega, phi. The transitions chi_c1 -> gamma rho^0 and chi_c1 -> gamma omega are observed with B(chi_c1 -> gamma rho^0) = (2.43 +- 0.19 +- 0.22) x 10^-4 and B(chi_c1 -> gamma omega) = (8.3 +- 1.5 +- 1.2) x 10^-5. In the chi_c1 -> gamma rho^0 transition, the final state meson is dominantly longitudinally polarized. Upper limits on the branching fractions of other chi_cJ states to light vector mesons are presented.

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arXiv2008

Dalitz plot analysis of the D^+ -> K^-pi^+pi^+ decay

We perform a Dalitz plot analysis of D^+ -> K^-pi^+pi^+ decay with the CLEO-c data set of 572 pb^-1 of e^+e^- collisions accumulated at the psi(3770). This corresponds to 1.6 million D^+D^- pairs from which we select 140793 candidate events with a small background of 1.1%. We compare our results with previous measurements using the isobar model. We modify the isobar model with improved description of some of the contributing resonances, and get better agreement with our data. We also consider a quasi-model-independent approach and measure the magnitude and phase of the contributing K pi S wave in the range of invariant masses from the threshold to the maximum in this decay. This gives an improved descriptions of our data over the isobar model. Finally we allow for an isospin-two pi^+pi^+ S-wave contribution, and find that adding this to both the isobar model and quasi-model-independent approach gives the best description of our data.

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