Guy Wilkinson

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.

Abstract:

We exploit the quantum coherence between pair-produced D0 and D̄0 in ψ(3770) decays to make a first determination of the relative strong phase differences between D0→KS0π+π- and D̄0→KS0π+π-, which are of great importance in determining the Cabibbo-Kobayashi-Maskawa angle γ/Φ3 in B-→D0(D̄0)K- decays. Using 818pb-1 of e+e- collision data collected with the CLEO-c detector at Ecm=3.77GeV, we employ a binned Dalitz-plot analysis of KS0π+π- and KL0π+π- decays recoiling against flavor-tagged, CP-tagged, and KS0π+π - tagged events to determine these strong phase differences. © 2009 The American Physical Society.

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.