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).Comment: 24 pages, 11 figures and 6 tables, v2 replaced some figure vertical axis scales, v3 corrections from PRD revie

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.Comment: 9 pages, available through http://www.lns.cornell.edu/public/CLNS/, submitted to PR

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.Comment: 9 pages, postscript also available through http://www.lns.cornell.edu/public/CLNS/2007/, revise

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.Comment: 11 pages, 3 figure

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.Comment: Version 2 updates include corrections to important errors in Table V and VII column headers which summarize results, and additional minor edits. 17 pages, available through http://www.lns.cornell.edu/public/CLNS

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.Comment: 10 pages, available through http://www.lns.cornell.edu/public/CLNS

Determination of the Strong Phase in D0 -> K+pi- Using Quantum-Correlated Measurements

We exploit the quantum coherence between pair-produced D0 and D0bar in psi(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase \delta between D0 -> K+pi- and D0bar -> K+pi-. Using 281 pb^-1 of e^+e^- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV, as well as branching fraction input and time-integrated measurements of R_M = (x^2+y^2)/2 and R_{WS} = Gamma(D0 -> K+pi-)/Gamma(D0bar -> K+pi-) from other experiments, we find \cos\delta = 1.03 +0.31-0.17 +- 0.06, where the uncertainties are statistical and systematic, respectively. By further including other mixing parameter measurements, we obtain an alternate measurement of \cos\delta = 1.10 +- 0.35 +- 0.07, as well as x\sin\delta = (4.4 +2.7-1.8 +- 2.9) x 10^-3 and \delta = 22 +11-12 +9-11 degrees.Comment: 5 pages, also available through http://www.lns.cornell.edu/public/CLNS/2007/. Incorporated referees' comment

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.Comment: 4 pages, available through http://www.lns.cornell.edu/public/CLNS/, submitted to Phys Rev D (Rapid Communications

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.Comment: 11 pages, available through http://www.lns.cornell.edu/public/CLNS

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.Comment: 7 pages, 3 figures, available through http://www.lns.cornell.edu/public/CLNS/, published in PRD Rapid Communication