Georg Viehhauser

Abstract:

Using a sample of 4.7 fb-1 integrated luminosity accumulated with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we investigate the mass spectrum and resonant structure in τ- →Κ-π+π-ντ decays. We measure the relative fractions of Κ1(1270) and Κ1(1400) resonances in these decays, as well as the Κ1 masses and widths. Our fitted Κ1 resonances are somewhat broader than previous hadroproduction measurements, and in agreement with recent CERN LEP results from tau decay. The larger central value of our measured width supports models which attribute the small τ-→Κ-π+π -ντ branching fraction to larger Κ1 widths than are presently tabulated. We also determine the Κa-Κb mixing angle θΚ. ©2000 The American Physical Society.

Abstract:

We describe a measurement of B0 - B̄0 mixing parameters exploiting a method of partial reconstruction of the decay chains B̄ → D(* ±)π(±) and B̄ → D(* ±) ρ (±). Using 9.6 x 106BB̄ pairs collected at the Cornell Electron Storage Ring, we find χ(d) = 0.198 ± 0.013 ± 0.014, |y(d)| < 0.40 at 95% confidence level, and |(R) e(ε(B)| < 0.034 at 95% confidence level. (C) 2000 Elsevier Science B.V.

Abstract:

We present a study of three B0 decay modes useful for time-dependent CP asymmetry measurements. From a sample of 9.7×106 BB̄ meson pairs collected with the CLEO detector, we have reconstructed B0 →J/ψKS0, B0→χclKS0, and B0→J/ψπ0 decays. The latter two decay modes have been observed for the first time. We describe a KS0→π0π0 detection technique and its application to the reconstruction of the decay B0 →J/ψKS0. Combining the results obtained using KS0→π+π- and KS0→π0π0 decays, we determine B(B0 →J/ψK0)=(9.5±0.8±0.6)×10-4, where the first uncertainty is statistical and the second one is systematic. We also obtain B(B0→χclK0)=(3.9-1.3+1.9±0.4)×10-4 and B(B0→J/ψπ0)=(2.5-0.9+1.1±0.2)×10-5. ©2000 The American Physical Society.

Abstract:

The decays B0→D*+D*-, B0→D*±D∓ and B0→D+D- are studied in 9.7 X 106 γ(4S)→BB̄ decays accumulated with the CLEO detector. We determine B(B0→D*+D*-) = (9.9+4.2-3.3[stat]±1.2[syst]) X 10-4 and limit B(B0→D*±D ∓)<6.3X10-4 and B(B0→D+D-)<9.4 X 10-4 at 90% confidence level (C.L.). We also perform the first angular analysis of the B0→D*+D*- decay and determine that the CP-even fraction of the final state is greater than 0.11 at 90% C.L. Future measurements of the time dependence of these decays may be useful for the investigation of CP violation in neutral B meson decays. ©2000 The American Physical Society.