Guy Wilkinson

Abstract:

One of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor and measurements and theoretical interpretations of their results have advanced tremendously: apart from masses and quantum numbers of flavor particles, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. Till early 1990s observations of CP violation were confined to neutral $K$ mesons, but since then a large number of CP-violating processes have been studied in detail in neutral $B$ mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of $K, D$, and $B$ mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field.

Abstract:

We study the inclusive decays of Ds+ mesons, using data collected near the Ds*±Ds peak production energy Ecm=4170MeV by the CLEO-c detector. We report the inclusive yields of Ds+ decays to K+X, K-X, KS0X, π+X, π-X, π0X, ηX, η′X, X, ωX, and f0(980)X, and also decays into pairs of kaons, Ds+→KK̄X. Using these measurements, we obtain an overview of Ds+ decays. © 2009 The American Physical Society.

Abstract:

Using data acquired with the CLEO-c detector at the CESR e+e- collider, we measure branching fractions for J/ψ, ψ(2S), and ψ(3770) decays to γπ0, γη, and γη′. Defining Rn B[ψ(nS)→γη]/B[ψ(nS)→γη′], we obtain R1=(21.1±0.9)% and, unexpectedly, an order of magnitude smaller limit, R2<1.8% at 90% C.L. We also use J/ψ→γη′ events to determine branching fractions of improved precision for the five most copious η′ decay modes. © 2009 The American Physical Society.

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.