Guy Wilkinson

Abstract:

We search for simultaneous baryon and lepton number violating decays of the D0 meson. Specifically, we use 281pb-1 of data taken on the ψ(3770) resonance with the CLEO-c detector at the CESR collider to look for decays D0→p̄e+, D̄0→p̄e+, D0→pe-, and D̄0→pe-. We find no significant signals and set the following branching fraction upper limits: D0→p̄e+(D̄0→p̄e+)<1.1×10-5 and D0→pe-(D̄0→pe-)<1.0×10-5, both at the 90% confidence level. © 2009 The American Physical Society.

Abstract:

We perform a Dalitz plot analysis of the decay Ds+→K+K-π+ with the CLEO-c data set of 586pb-1 of e+e- collisions accumulated at s=4.17GeV. This corresponds to about 0.57×106 Ds±Ds* pairs from which we select 14400 candidates with a background of roughly 15%. In contrast to previous measurements we find good agreement with our data only by including an additional f0(1370)π+ contribution. We measure the magnitude, phase, and fit fraction of K*(892)0K+, (1020)π+, K0*(1430)K+, f0(980)π+, f0(1710)π+, and f0(1370)π+ contributions and limit the possible contributions of other KK and Kπ resonances that could appear in this decay. © 2009 The American Physical Society.

Abstract:

Using a sample of 2.59×107 ψ(2S) decays collected by the CLEO-c detector, we present results of a study of χc0 and χc2 decays into two-meson final states. We present the world's most precise measurements of the χcJ,(J=0,2)→π+π-, π0π0, K+K-, KS0KS0, ηη, and η′η′ branching fractions, and a search for χc decays into ηη′. These results shed light on the mechanism of charmonium decays into pseudoscalar mesons. © 2009 The American Physical Society.

Abstract:

We have studied the leptonic decay Ds+→τ+ντ, via the decay channel τ+→e+νeν̄τ, using a sample of tagged Ds+ decays collected near the Ds*±Ds peak production energy in e+e- collisions with the CLEO-c detector. We obtain B(Ds+→τ+ντ)=( 5.30±0.47±0.22)% and determine the decay constant fDs=(252.5±11.1± 5.2)MeV, where the first uncertainties are statistical and the second are systematic. © 2009 The American Physical Society.

Abstract:

We examine e+e-→Ds-Ds*+ and Ds*-Ds+ interactions at 4170 MeV using the CLEO-c detector in order to measure the decay constant fDs+ with good precision. Previously our measurements were substantially higher than the most precise lattice based QCD calculation of (241± 3)MeV. Here we use the Ds+→+ν channel, where the + designates either a μ+ or a τ+, when the τ+→π+ν̄. Analyzing both modes independently, we determine B(Ds+→μ+ν)=( 0.565±0.045±0.017)%, and B(Ds+→τ+ν)=(6.42±0.81± 0.18)%. We also analyze them simultaneously to find an effective value of Beff(Ds+→μ+ν)=(0.591± 0.037±0.018)% and fDs+=( 263.3±8.2±3.9)MeV. Combining with the CLEO-c value determined independently using Ds+→τ+ν, τ+→e+νν̄ decays, we extract fDs+=( 259.5±6.6±3.1)MeV. Combining with our previous determination of B(D+→μ+ν), we extract the ratio fDs+/fD+=1.26±0.06±0.02. No evidence is found for a CP asymmetry between Γ(Ds+→μ+ν) and Γ(Ds-→μ-ν); specifically the fractional difference in rates is measured to be (4.8±6.1)%. Finally, we find B(Ds+→e+ν)<1.2×10-4 at 90% confidence level. © 2009 The American Physical Society.