Georg Viehhauser

Abstract:

We report results of a search for the rare radiative decay B̄0 → D0γ. Using 9.66 × 10 6 BB̄ meson pairs collected with the CLEO detector at the Cornell Electron Storage Ring, we set an upper limit on the branching ratio for this decay of 5.0× 10-5 at 90% C.L. This provides evidence that the anomalous enhancement is absent in W-exchange processes and that weak, radiative B decays are dominated by the short-distance b → sγ mechanism in the standard model. © 2000 The American Physical Society.

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.