Georg Viehhauser

Abstract:

This article describes improved measurements by CLEO of the B0→Ds+D*- and B0→Ds*+D*- branching fractions, and first evidence for the decay B+→Ds(*)+D̄** 0, where D̄**0 represents the sum of the D̄1(2420)0, D̄2*(2460)0, and D̄1(j = 1/2)0 L = 1 charm meson states. Also reported is the first measurement of the Ds*+ polarization in the decay B0→Ds*+D*-. A partial reconstruction technique, employing only the fully reconstructed Ds+ and slow pion πs- from the D*-→D̄0πs- decay, enhances sensitivity. The observed branching fractions are B(B0→Ds+D*-) = (1.10±0.18±0.10±0.28)%, B(B0→Ds*+D*-) = (1.82±0.37±0.24 ±0.46)% , and B(B+→Ds(*) +D̄**0) = (2.73±0.78±0.48±0.68)%, where the first error is statistical, the second systematic, and the third is the uncertainty in the Ds+→φπ+ branching fraction. The measured Ds*+ longitudinal polarization, ΓL/Γ = (50.6±13.9±3.6)%, is consistent with the factorization prediction of 54%.

Abstract:

The resonant structure of the four pion final state in the decay τ→3 ππ 0 ν τ 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 τ→3 ππ 0 ν τ decay has been performed; the spectral decomposition of the four pion system is dominated by the ωπ and a 1 π final states. The mass and width of the ρ′ resonance have been extracted from a fit to the τ→ωπν τ spectral function. We have searched for second class currents in the decay τ→ωπν τ using spin-parity analysis and established an upper limit on the non-vector current contribution. © 2000 The American Physical Society.

Abstract:

Based on a high statistics e+e-→cc̄ data sample, we report on the inclusive rate for charmed baryons to decay into Λ particles using charm-event tagging. We select e+e-→cc̄ events which have a clear anti-charm tag and measure the Λ content in the hemisphere opposite the tag (charge conjugate modes are implicit). This allows us to determine the product branching fraction BΛ=B(c→ΘcX)XB(Θ c→ΛX), where Θc represents a sum over all charmed baryons produced in e+e- fragmentation at √s=10.5 GeV, given our specific tags. We obtain BΛ=(1.87±0.03±0.33)%. ©2000 The American Physical Society.