Georg Viehhauser

Abstract:

A measurement of the spin alignment of charged D* mesons produced in continuum e⁺e^-→cc̄ events at √s = 10.5 GeV is presented. This study using 4.72 fb^-1 of CLEO II data shows that there is little evidence of any D* spin alignment.

Abstract:

Using a 73.6 pb^-1 data sample of Y(2S) events collected with the CLEO II detector at the Cornell Electron Storage Ring, we have investigated the hadronic transitions between the Y(2S) and the Y(1S). The dipion transition Y(2S)→Y(1S)π⁺π was studied using two different analysis techniques. Selecting events in which Y(1S)→e⁺e^-,μ⁺μ^- ("exclusive" analysis), and using the Y(1S) leptonic branching fractions world averages from the PDG review, we obtained B(Y(2S)→Y(1S)π⁺π^-) = 0.189±0.004±0.010, while using a method allowing Y(1S)→anything ("inclusive" analysis) we obtained B(Y(2S)→Y(1S)π⁺π^- = 0.196 ±0.002±0.010. The appropriate weighted average of the two measurements gives B(Y(2S) →Y(1S)μ⁺μ^-) = 0.192±0.002±0.010. Combining the exclusive and inclusive results we derive the Y(1S) leptonic branching fractions Bee = 0.0229±0.0008±0.0011 and Bμμ = 0.0249±0.0008±0.0013. We also studied Y(2S)→Y(1S)π⁰π⁰ and obtained B(Y(2S)→Y(1S)π⁰π⁰) = 0.092±0.006±0.008. Parameters of the ππ system (dipion invariant mass spectra, angular distributions) were analyzed and found to be consistent with current theoretical models. Lastly, we searched for the η and single π⁰ transitions and obtained the 90% confidence level upper limits B(Y(2S)→Y(1S)η)<0.0028 and B(Y(2S)→Y(1S)π⁰)<0.0011.

Abstract:

Using a data sample with an integrated luminosity of 3.9 fb collected in e e annihilation with the CLEO-II detector at the Cornell Electron Storage Ring, we have measured the branching ratios for the decay modes D → (η,η′)π and D →(η,η′)ρ relative to D → φπ . These decay modes are among the most common hadronic decays of the D , and can be related by factorization to the semileptonic decays D →(η,η′)ℓ ν . The results obtained are compared with previous CLEO results and with the branching ratios measured for the related semileptonic decays. We also report results on the Cabibbo-suppressed decays of the D to the same final states.

Abstract:

We present a new determination of f^Ds using 5 million e⁺e^-→cc̄ events obtained with the CLEO II detector. Our value is derived from our new measured ratio Γ(D⁺s → μ⁺ν)/Δ(D⁺s → φπ⁺) = 0.173 ± 0.023 ± 0.035. Using ß(D^+s → φπ⁺) = (3.6 ± 0.9)%, we extract fDs = (280 ± 19 ± 28 ± 34) MeV. We compare this result with various model calculations.

Abstract:

We have searched for two-body charmless decays of B mesons to purely hadronic exclusive final states including ω or φ mesons using data collected with the CLEO II detector. With this sample of 6.6 ×106B mesons we observe a signal for the ωK+ final state, and measure a branching fraction of B(B+→ωK+)=(1.5−0.6+0.7)±0.2)×10−5We also observe some evidence for the φK* final state, and upper limits are given for 22 other decay modes. These results provide the opportunity for studies of theoretical models and physical parameters. © 1998 American Physical Society.