Guy Wilkinson

Abstract:

Using a sample of 2.59×107 ψ(2S) decays collected by the CLEO-c detector, we present results of a search for the decay chain ψ(2S)→π0hc, hc→n(π+π-)π0, n=1, 2, 3. We observe no significant signals for n=1 and n=3 and set upper limits for the corresponding decay rates. First evidence for the decay hc→π+π-π+π-π0 is presented, and a product branching fraction of B(ψ(2S)→hcπ0) ×B(hc→2(π+π-)π0)=1.88-0.45-0.30+0.48+0.47×10-5 is measured. This result implies that hc→hadrons and hc→γηc have comparable rates, in agreement with expectations. © 2009 The American Physical Society.

Abstract:

Using data collected near the Ds* ± Ds Ds peak production energy E cm 4170 MeV by the CLEO-c detector, we search for Ds+ exclusive hadronic decays involving. We find B Ds+ n+ w 0.21 ± 0.09 ± %, B Ds+ n+ 2.78 ± 0.65 ± 0.25 %, Ds+ n+ n+ n- 1.58 ± 0.09%. Ds+ n+ 0.85± 0.54 ± 0.06%. K+. n+ n- 0.54%, and The upper limits are at 90% confidence level.

Abstract:

The first measurements of the coherence factors (RKππ0 and RK3π) and the average strong-phase differences (δDKππ0 and δDK3π) for D0→K-π+π0 and D0→K-π+π+π- are presented. These parameters can be used to improve the determination of the unitarity triangle angle γ in B-→DK- decays, where D is a D0 or D̄0 meson decaying to the same final state. The measurements are made using quantum-correlated, fully reconstructed D0D̄0 pairs produced in e+e- collisions at the ψ(3770) resonance. The measured values are: RKππ0=0.84±0.07, δDKππ0=(227-17+14)°, RK3π=0.33-0.23+0.20, and δDK3π=(114-23+26)°. These results indicate significant coherence in the decay D0→K-π+π0, whereas lower coherence is observed in the decay D0→K-π+π+π-. The analysis also results in a small improvement in the knowledge of other D-meson parameters, in particular, the strong-phase difference for D0→K-π+, δDKπ, and the mixing parameter y. © 2009 The American Physical Society.

Abstract:

Using the entire CLEO-c ψ(3770)→DD̄ event sample, corresponding to an integrated luminosity of 818pb-1 and approximately 5.4×106 DD̄ events, we present a study of the decays D0→π-e+νe, D0→K-e+νe, D+→π0e+νe, and D+→K̄0e+νe. Via a tagged analysis technique, in which one D is fully reconstructed in a hadronic mode, partial rates for semileptonic decays by the other D are measured in several q2 bins. We fit these rates using several form factor parametrizations and report the results, including form factor shape parameters and the branching fractions B(D0→π-e+νe)=(0.288±0. 008±0.003)%, B(D0→K-e+νe)=(3.50±0.03±0.04)%, B(D+→π0e+νe)=(0.405±0.016±0.009)%, and B(D+→K̄0e+νe)=(8.83±0.10±0.20)%, where the first uncertainties are statistical and the second are systematic. Taking input from lattice quantum chromodynamics, we also find |Vcd|=0.234±0.007±0. 002±0.025 and |Vcs|=0.985±0.009±0.006±0.103, where the third uncertainties are from lattice quantum chromodynamics. © 2009 The American Physical Society.