Guy Wilkinson

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.

Abstract:

We search for a non-SM-like CP-odd Higgs boson (a10) decaying to τ+τ- or μ+μ- in radiative decays of the Υ(1S). No significant signal is found, and upper limits on the product branching ratios are set. Our τ+τ- results are almost 2 orders of magnitude more stringent than previous upper limits. Our data provide no evidence for a Higgs state with a mass of 214 MeV decaying to μ+μ-, previously proposed as an explanation for 3 Σ+→pμ+μ- events observed by the HyperCP experiment. Our results constrain NMSSM models. © 2008 The American Physical Society.

Abstract:

We report on a search for CP asymmetry in the singly Cabibbo-suppressed decay D+→K+K-π+ using a data sample of 818pb-1 accumulated with the CLEO-c detector on the ψ(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)%. © 2008 The American Physical Society.

Abstract:

Using a total of 2.74×107 decays of the ψ(2S) collected with the CLEO-c detector, we present a study of χcJ→γV, where V=ρ0, ω, □. The transitions χc1→γρ0 and χc1→γω are observed with B(χc1→γρ0)=(2. 43±0.19±0.22)×10-4 and B(χc1→γω)=(8. 3±1.5±1.2)×10-5. In the χc1→γρ0 transition, the final state meson is dominantly longitudinally polarized. Upper limits on the branching fractions of other χcJ states to light vector mesons are presented. © 2008 The American Physical Society.

Abstract:

We measure the branching ratio of the purely leptonic decay of the D+ meson with unprecedented precision as B(D+→μ+ν)=(3.82±0. 32±0.09)×10-4, using 818pb-1 of data taken on the ψ(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 Γ(D+→μ+ν)-Γ(D-→μ-ν̄)Γ(D+→μ +ν)+Γ(D-→μ-ν̄)=0.08±0.08, consistent with no CP violation. We also set 90% confidence level upper limits on B(D+→τ+ν )<1.2×10-3 and B(D+→e+ν)<8.8×10-6. © 2008 The American Physical Society.