Guy Wilkinson

Abstract:

Using data collected on the ψ(3770) resonance and near the Ds*±Ds" peak production energy by the CLEO-c detector, we study the decays of the possible D→PP modes and report measurements of or upper limits on all branching fractions for Cabibbo-favored, singly Cabibbo-suppressed, and doubly Cabibbo-suppressed D→PP decays except modes involving KL0 (and except D0→K+π-). We normalize with respect to the Cabibbo-favored D modes, D0→K -π+, D+→K-π +π+, and Ds+→K+KS0. © 2010 The American Physical Society.

Abstract:

We have measured the inclusive semileptonic branching fractions of D0, D+, and Ds+ mesons. For these measurements, we have used the full CLEO-c open-charm data samples, 818pb-1 at ECM=3.774GeV, giving D0D̄0 and D+D- events, and 602pb -1 at ECM=4.170GeV, giving Ds*±Ds" events. We obtain B(D0→Xe+νe)=(6.46±0.09±0.11)%, B(D +→Xe+νe)=(16.13±0.10±0.29)%, and B(Ds+→Xe+νe)=(6.52±0.39±0.15)%, where the first uncertainties are statistical and the second are systematic. From these and lifetimes obtained elsewhere, we obtain the ratios of semileptonic decay widths Γ(D+→Xe+νe)/Γ(D0→Xe +νe)=0.985±0.015±0.024 and Γ(Ds+→Xe +νe)/Γ(D0→Xe+νe)=0.828±0. 051±0.025. The ratio of D+ and D0 is consistent with the isospin symmetry prediction of unity, and the ratio of Ds+ and D0 differs from unity, as expected. © 2010 The American Physical Society.

Abstract:

We report a search for the decay ψ(2S)→γηc(2S) in a sample of 25.9×106 ψ(2S) events collected with the CLEO-c detector. No signals are observed in any of the 11 exclusive ηc(2S) decay modes studied, or in their sum. Product branching fraction upper limits are determined as a function of Γ[ηc(2S)] for the 11 individual modes. © 2010 The American Physical Society.

Abstract:

We report evidence for the ground state of bottomonium, ηb(1S), in the radiative decay Υ(3S)→γηb in e+e- annihilation data taken with the CLEO III detector. Using 6×106 Υ(3S) decays, and assuming Γ(ηb)=10±5MeV/c2, we obtain B(Υ(3S)→γηb)=(7.1±1.8±1.3)×10 -4, where the first error is statistical and the second is systematic. The statistical significance is ∼4σ. The mass is determined to be M(ηb)=9391.8±6.6±2.0MeV/c2, which corresponds to the hyperfine splitting ΔMhf(1S)b=68.5±6.6±2.0MeV/c2. Using 9×106 Υ(2S) decays, we place an upper limit on the corresponding Υ(2S) decay, B(Υ(2S)→γηb)<8. 4×10-4 at 90% confidence level. © 2010 The American Physical Society.

Abstract:

In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved; apart from their masses and quantum numbers, 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. In the past, observations of CP violation were confined to neutral . K mesons, but since the early 1990s, 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 is the result of the work of physicists attending the 5th CKM workshop, hosted by the University of Rome "La Sapienza", September 9-13, 2008. It summarizes the results of the current generation of experiments that are about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade. © 2010 Elsevier B.V.