Higher-order multipole amplitudes in charmonium radiative transitions

Using 24 million $\psi' \equiv \psi(2S)$ decays in CLEO-c, we have searched for higher multipole admixtures in electric-dipole-dominated radiative transitions in charmonia. We find good agreement between our data and theoretical predictions for magnetic quadrupole (M2) amplitudes in the transitions $\psi' \to \gamma \chi_{c1,2}$ and $\chi_{c1,2} \to \gamma J/\psi$, in striking contrast to some previous measurements. Let $b_2^J$ and $a_2^J$ denote the normalized M2 amplitudes in the respective aforementioned decays, where the superscript $J$ refers to the angular momentum of the $\chi_{cJ}$. By performing unbinned maximum likelihood fits to full five-parameter angular distributions, we determine the ratios $a_2^{J=1}/a_2^{J=2} = 0.67^{+0.19}_{-0.13}$ and $a_2^{J=1}/b_2^{J=1} = -2.27^{+0.57}_{-0.99}$, where the theoretical predictions are independent of the charmed quark magnetic moment and are $a_2^{J=1}/a_2^{J=2} = 0.676 \pm 0.071$ and $a_2^{J=1}/b_2^{J=1} = -2.27 \pm 0.16$.Comment: 32 pages, 7 figures, acceptance updat

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.Comment: 14 pages, available through http://www.lns.cornell.edu/public/CLNS/, published in Physical Review

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

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

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

Measurement of the Masses and Widths of the Sigma_c^++ and Sigma_c^0 Charmed Baryons

Using data recorded by the CLEO II and CLEO II.V detector configurations at CESR, we report new measurements of the masses of the Sigma_c^{++} and Sigma_c^0 charmed baryons, and the first measurements of their intrinsic widths. We find M(Sigma_c^{++}) - M(Lambda_c^+) = 167.4 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^{++}) = 2.3 +- 0.2 +- 0.3 MeV, and M(Sigma_c^0) - M(Lambda_c^+) = 167.2 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^0) = 2.5 +- 0.2 +- 0.3 MeV, where the uncertainties are statistical and systematic, respectively.Comment: 9 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PRD, Rapid Communications. Reference [13] correcte

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

Search for psi(2S) -> gamma eta_c(2S) via fully reconstructed eta_c(2S) decays

We report a search for the decay psi(2S) -> gamma eta_c(2S) in a sample of 25.9 million psi(2S) events collected with the CLEO-c detector. No signals are observed in any of the 11 exclusive eta_c(2S) decay modes studied, or in their sum. Product branching fraction upper limits are determined as a function of Gamma[eta_c(2S)] for the 11 individual modes.Comment: 21 pages, 7 figures, updated to published version (PRD 81, 052002 (2010)