Georg Viehhauser

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.

Abstract:

A limit on the mass of the tau neutrino mντ is derived from 4.5 × 106 tau pairs produced in an integrated luminosity of 5.0 fb-1 of e+e- → γ * → τ+τ- reactions at center of mass energies ≈ 10.6 GeV. The measurement technique involves a two-dimensional extended likelihood analysis, including the dependence of the end-point population on mντ, and allows for the first time an explicit background contribution. We use the the decays τ → 5πντ and τ → 3π2π0ντ to obtain an upper limit of 30 MeV/c2 at 95% C.L. © 1998 Elsevier Science B.V. All rights reserved.

Abstract:

The CLEO collaboration is preparing a major upgrade of its present detector including a RICH detector for particle identification. This subdetector system follows the 'proximity focussing' design and uses Lithium Fluoride (LiF) crystal radiators and MWPCs as photon detectors. These chambers are filled with a CH4/TEA gas mixture and have a Calcium Fluoride (CaF2) crystal photon entrance window. Part of the radiator crystals will have the new 'sawtooth' geometry.We have constructed two of the 30 detector modules and tested these together with the first planar and 'sawtooth' radiator crystals in a muon halo beam at Fermilab. For the measurement of the Cherenkov angle we obtain a single photon measurement error of 13.5 mrad for the conventional planar radiator. With 14 detected photons we find a resolution per track of 4.5 mrad. In the first measurement ever of a 'sawtooth' radiator we achieve a resolution of 11.8 mrad for single photons and 4.8 mrad per track for 12.3 detected photons With a reduced geometric acceptance. These results fulfill CLEO III requirements.