Guy Wilkinson

Abstract:

Using ψ(3770)→DD̄ 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→π-e+νe, D+→π0e+νe, D0→K-e+νe, and D+→K̄0e+νe. 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+π(0)|Vcd| and f+K(0)|Vcs|, we find |Vcd|=0.222(8)(3)(23) and |Vcs|=1.018(10)(8)(106), where the uncertainties are statistical, experimental systematic, and from LQCD, respectively. © 2009 The American Physical Society.

Abstract:

Measurements are presented of R b, the ratio of the cross-section to the cross-section in e+e- collisions, and the forward-backward asymmetry A FBb at twelve energy points in the range sqrt{s}=130-207 GeV. These results are found to be consistent with the Standard Model expectations. The measurements are used to set limits on new physics scenarios involving contact interactions. © 2009 Springer-Verlag / Società Italiana di Fisica.

Abstract:

Using ψ(2S)→π+π-J/ψ, J/ψ→γη′ events acquired with the CLEO-c detector at the CESR e+e- collider, we make the first observations of the decays η′→π+π-π0 and η′→π+π-e+e-, measuring absolute branching fractions (37-9+11±4)×10-4 and (25-9+12±5)×10-4, respectively. For η′→π+π-π0, this result probes the mechanism of isospin violation and the roles of π0/η/η′-mixing and final state rescattering in strong decays. We also set upper limits on branching fractions for η′ decays to π+π-μ+μ-, 2(π+π-), π+π-2π0, 2(π+π-)π0, 3(π+π-), and invisible final states. © 2009 The American Physical Society.

Abstract:

Using samples of (5.93±0.10)×106 Υ(3S) decays and (9.11±0.14)×106 Υ(2S) decays collected with the CLEO detector, we report improved measurements of the following branching fractions: B(Υ(3S)→Υ(1S)π+π-)=(4.46±0.01±0.13)%, B(Υ(2S)→Υ(1S)π+π-)=(18.02±0.02±0.61)%, B(Υ(3S)→Υ(1S)π0π0)=(2.24±0.09±0.11)%, B(Υ(2S)→Υ(1S)π0π0)=(8.43±0.16±0.42)%, and B(Υ(3S)→Υ(2S)π0π0)=(1.82±0.09±0.12)%. In each case, the first uncertainty reported is statistical, while the second is systematic. © 2009 The American Physical Society.

Abstract:

Using 2.45×107 ψ(2S) decays collected with the CLEO-c detector at the Cornell Electron Storage Ring we present the most precise measurements of magnetic dipole transitions in the charmonium system. We measure B(ψ(2S)→γηc)=(4.32±0.16±0.60)×10-3, B(J/ψ→γηc)/B(ψ(2S)→γηc)=4.59±0. 23±0.64, and B(J/ψ→γηc)=(1.98±0.09±0.30) %. We observe a distortion in the ηc line shape due to the photon-energy dependence of the magnetic dipole transition rate. We find that measurements of the ηc mass are sensitive to the line shape, suggesting an explanation for the discrepancy between measurements of the ηc mass in radiative transitions and other production mechanisms. © 2009 The American Physical Society.