Guy Wilkinson

Abstract:

Analyzing Y(nS) decays acquired with the CLEO detector operating at the CESR e+e- collider, we measure for the first time the product branching fractions B[Y(nS)→YX bJ((n-1)P)]B[X bJ(n-1)P)→Xi] for n=2 and 3, where Xi denotes, for each i, one of the 14 exclusive light-hadron final states for which we observe significant signals in both X bJ(1P) and X bJ(2P) decays. We also determine upper limits for the electric dipole (E1) transitions Y(3S)→YX bJ(1P). © 2008 The American Physical Society.

Abstract:

We report the first observation of Υ(2S)→ηΥ(1S), with a branching fraction B=(2.1-0.6+0.7(stat)±0.3(syst))×10-4 and a statistical significance 5.3σ. Data were acquired with the CLEO III detector at the CESR e+e- symmetric collider. This is the first process observed involving a b-quark spin flip. For related transitions, 90% confidence limits in units of 10-4 are B(Υ(2S)→π0Υ(1S))<1.8, B(Υ(3S)→ηΥ(1S))<1.8, B(Υ(3S)→π0Υ(1S)) <0.7, and B(Υ(3S)→π0Υ(2S))<5.1. © 2008 The American Physical Society.

Abstract:

We measure the mass of the eta;{'} meson using psi(2S)-->pi;{+}pi;{-}J/psi, J/psi-->gammaeta;{'} events acquired with the CLEO-c detector operating at the CESR e;{+}e;{-} collider. Using three decay modes, eta;{'}-->rho;{0}gamma, eta;{'}-->pi;{+}pi;{-}eta with eta-->gammagamma, and eta;{'}-->pi;{+}pi;{-}eta with eta-->pi;{+}pi;{-}pi;{0}, we find M_{eta;{'}}=957.793+/-0.054+/-0.036 MeV, in which the uncertainties are statistical and systematic, respectively. This result is consistent with but substantially more precise than the current world average.

Abstract:

A precision measurement of the mass of the hc(P11) state of charmonium has been made using a sample of 24.5×106 ψ(2S) events produced in e+e- annihilation at the Cornell Electron Storage Ring (CESR). The reaction used was ψ(2S)→π0hc, π0→γγ, hc→γηc, 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 ηc decays are reconstructed in 15 hadronic decay channels. Consistent results are obtained in the two analyses. The averaged results of the present measurements are M(hc)=3525.28±0.19(stat.)±0.12(syst.)MeV, and B(ψ(2S)→π0hc)×B(hc→γηc)=(4.19±0. 32±0.45)×10-4. Using the PJ3 centroid mass, ΔMhf(1P) M(χcJ) -M(hc)=+0.02±0.19±0.13MeV. © 2008 The American Physical Society.

Abstract:

We measure the mass of the η′ meson using ψ(2S) →π+π-J/ψ, J/ψ→γη′ events acquired with the CLEO-c detector operating at the CESR e+e- collider. Using three decay modes, η′→ρ0γ, η′→π+π-η with η→γγ, and η′→π+π-η with η→π+π-π0, we find Mη′=957.793±0.054±0. 036MeV, in which the uncertainties are statistical and systematic, respectively. This result is consistent with but substantially more precise than the current world average. © 2008 The American Physical Society.