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.

Abstract:

We search for the decay of the B⁰ meson into a pair of leptons in the suppressed channels B⁰→e⁺e^-, B⁰→μ⁺μ^- and in the lepton number violating channel B⁰→e^±μ^∓ in a sample of 9.7×10⁶ BB̄ pairs recorded by CLEO detector. No signal is found, and the following upper limits on the branching fractions are established: B(B⁰→e⁺e^-)<8.3×10^-7, B(B⁰→μ⁺μ^-)<6.1×10 ^-7, B(B⁰→e^±μ ^∓)<15×10^-7 at 90% confidence level. A new lower limit on the Pati-Salam leptoquark mass MLQ>27 TeV is established at 90% confidence level. © 2000 The American Physical Society.