Georg Viehhauser

Abstract:

The resonant structure of the four pion final state in the decay τ→3ππ⁰ντ has been analyzed using 4.27 million τ⁺τ^- pairs collected by the CLEO II experiment at the Cornell Electron Storage Ring. A partial wave analysis of the resonant structure of the ô-»3 τ→3ππ⁰ντ decay has been performed; the spectral decomposition of the four pion system is dominated by the ωπ and a1π final states. The mass and width of the ρ′ resonance have been extracted from a fit to the τ→ωπντ spectral function. We have searched for second class currents in the decay τ→ωπντ using spin-parity analysis and established an upper limit on the non-vector current contribution. ©2000 The American Physical Society.

Abstract:

We present an update of the search for the lepton family number violating decay τ→μγ using 12.6 million τ+τ- pairs collected with the CLEO detector. No evidence of a signal has been found and the corresponding upper limit is script B sign(τ→μγ)<1.1×10-6 at 90% C.L., significantly smaller than previous experimental limits. ©2000 The American Physical Society.

Abstract:

From a data sample of 29058 τ^±→π^±π⁺π ^-π⁰vτdecays observed in the CLEO detector we derive a 95% confidence upper limit on the tau neutrino mass of 28 MeV. ©2000 The American Physical Society.

Abstract:

Using a sample of 3.3×10⁶ Y(4S)→BB̄ events collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we measure B(B→ρlv), |Vub|, and the partial rate (ΔΓ) in three bins of q²≡(pB -pρ)². We find B(B⁰→ρ^-l+v)=(2.69±0.41 -0.40^+0.35±0.50)×10^-4, |Vub|=(3.23±0.24-0.26^+0.23 ±0.58)×10^-3, ΔΓ(02<7 GeV²/c⁴)=(7.6±3.0-1.2 ^+0.9±3.0)×10^-2 ns^-1, ΔΓ(72<14 GeV²/c⁴)=(4.8 ±2.9-0.8^+0.7±0.7)×10^-2 ns^-1, and ΔΓ(142<21 GeV²/c⁴)=(7.1±2.1-1.1 ^+0.9±0.6)×10^-2 ns^-1. Here, l=e or μ, but not both, and the errors are statistical, systematic, and theoretical. The method is sensitive primarily to B→ρlv decays with leptons in the energy range above 2.3 GeV. Averaging with the previously published CLEO results for B→ρlv, we obtain B(B⁰→ρ^-l⁺v)=(2.57±0.29 -0.46^+0.33±0.41)×10^-4 and |Vub|=(3.25 ±0.14-0.29^+0.21±0.55)×10^-3. ©2000 The American Physical Society.

Abstract:

The CLEO III Ring Imaging Cherenkov detector uses LiF radiators to generate Cherenkov photons which are then detected by proportional wire chambers using a mixture of CH4 and TEA gases. The first two photon detector modules which were constructed, were taken to the Fermilab and tested in a beam dump that provided high-momentum muons. We report on results using both plane and 'sawtooth'-shaped radiators. Specifically, we discuss the number of photoelectrons observed per ring and the angular resolution. The particle separation ability is shown to be sufficient for the physics of CLEO III.