Georg Viehhauser

Abstract:

Using a 4.19 fb -1 data sample collected with the CLEO II detector at the Cornell Electron Storage Ring, we have searched for dipion transitions between pairs of Y resonances at center of mass energies E c.m. = 10.58 GeV and E c.m. = 10.52GeV. We obtain the 90% confidence level upper limits B(Y(4S) →Y(2S)π + π - )<3.9×10 -4 and B(Y(4S)→Y(1S)π + π - )<1.2×10 -4 . We also observe the transitions Y(3S)→Y(1S)π + π - , Y(3S)→Y(2S)π + π - , and Y(2S)→Y(1S)π + π - , from which we measure the cross sections for the radiative processes e + e - →Y(3S)γ and e + e - →Y(2S)γ. We obtain σ ee→Y(3S)γ = (17.8±3.0±1.7) pb and σ ee→Y(2S)γ =(15.5±1.3±1.4) pb at E c.m. = 10.58 GeV, and σ ee→Y(3S)γ =(27.3±5.0±2.6) pb and σ ee→Y(2S)γ =(16.3±1.8±1.5) pb at E c.m. = 10.52 GeV, which we compare with theoretical predictions. ©1999 The American Physical Society.

Abstract:

The CLEO-III detector upgrade for charged particle identification is discussed. The RICH design uses solid LiF crystal radiators coupled with multi-wire chamber photon detectors, using TEA as the photosensor, and low-noise Viking readout electronics. Results from our beam test at Fermilab are presented. (C) 1999 Elsevier Science B.V. All rights reserved.

Abstract:

We report the results of a search for the rare baryonic decay modes B0→ΛΛ̄, B+→Λ̄p, B0→Λ̄pπ-, and B0→pp̄ (and their charge conjugate states) using 5.8 × 106 BB̄ pairs collected with the CLEO detector. We see no statistically significant signals in any of these modes and set 90% confidence level upper limits on their branching fractions, B(B0→ΛΛ̄)<3.9 × 10-6, B(B+→Λ̄p)<2.6 × 10-6, B(B0→Λ̄pπ-)<1.3 × 10-5 and B(B0→pp̄)<7.0 × 10-6. ©1999 The American Physical Society.

Abstract:

We have searched for five decay modes of the τ lepton that simultaneously violate lepton and baryon number: τ^-→p̄γ, τ^-→p̄π⁰, τ^-→p̄η, τ^-→p̄2π⁰, and τ^-→p̄π⁰η. The data used in the search were collected with the CLEO II detector at the Cornell Electron Storage Ring. The integrated luminosity of the data sample is 4.7 fb^-1, corresponding to the production of 4.3 × 10⁶ τ⁺τ^- events. No evidence is found for any of the decays, resulting in much improved upper limits on the branching fractions for the two-body decays and first upper limits for the three-body decays. ©1999 The American Physical Society.