Georg Viehhauser

Abstract:

We report on a study of exclusive radiative decays of the ϒ(1S) resonance collected with the CLEO II detector operating at the Cornell Electron Storage Ring. We present the first observation of the radiative decays ?(1S)→γπ+#x03C0;- and ϒ(1S)→ γ #x03C0;0#x03C0;0. For the dipion mass regime m#x03C0;#x03C0; > 1.0 GeV we obtain B(ϒ(1S)→ γ#x03C0;+#x03C0;-)=(6.3±1.2±1.3)×10-5 and B(ϒ(1S)→ γ#x03C0;0#x03C0;0)=(1.7±0.6±0.3)×10-5. © 2000 The American Physical Society.

Abstract:

We have observed four fully reconstructed B⁰ → D^* + D^*- candidates in 5.8×106 ϒ(4S) → BB decays recorded with the CLEO detector. The background is estimated to be 0.31±0.10 events. The probability that the background could produce four or more signal candidates with the observed distribution among D^*+ and D^*- decay modes is 1.1 × 10^-4. The measured decay rate, B(B⁰ → D^*+D^*-) = [6.2^+4.0 -2.9(stat) ± 1.0(syst)] × 10^-4, is large enough for this decay mode to be of interest for the measurement of a time-dependent CP asymmetry. © 1999 The American Physical Society.

Abstract:

We report measurements of the D⁰, D⁺, and D⁺ s meson lifetimes using 3.7fb^-1 of e⁺e^- annihilation data collected near the ϒ(4S) resonance with the CLEO detector. The measured lifetimes of the D⁰, D⁺, and D⁺ s mesons are 408.5 ± 4.1^+3.5 -3.4 fs, 1033.6 ± 22.1^+9.9 -12.7 fs, and 486.3 ± 15.0^+4.9 -5.1 fs. The precisions of these lifetimes are comparable to those of the best previous measurements, and the systematic errors are very different. In a single experiment we find that the ratio of the D⁺ s and D⁰ lifetimes is 1.19 ± 0.04. © 1999 The American Physical Society.

Abstract:

Using a sample of 3.3 × 10⁶ B-meson decays collected with the CLEO detector at the Cornell Electron Storage Ring, we have studied B^- → D⁰ℓ^-ν and B⁰ → D⁺ℓ^-ν decays, where ℓ^- can be either e^- or μ^-. We distinguish B → Dℓν from other B semileptonic decays by examining the net momentum and energy of the particles recoiling against D - ℓ pairs. We find Γ(B → Dℓν) = (14.1±1.0±1.2)ns^-1 and derive branching fractions for B^- → D⁰ℓ^-ν and B⁰ → D⁺ℓ^-ν of (2.32±0.17±0.20)% and (2.20±0.16±0.19)%, respectively, where the uncertainties are statistical and systematic. We also investigate the B → Dℓν form factor and the implication of the result for |Vcb|. © 1999 The American Physical Society.

Abstract:

We report the first observation of two narrow charmed strange baryons decaying to Ξ+cγ and Ξ0Cγ, respectively, using data from the CLEO II detector at the Cornell Electron Storage Ring. We interpret the observed signals as the Ξ+′c(c(u)) and Ξ0′cγ(c(sd)), the symmetric partners of the well-established antisymmetric Ξ+c(c[su]) and Ξ0c(c[sd]). The mass differences M(Ξ+′c)-M(Ξ+c) and M(Ξ0′c)-M(Ξ0c) have been measured to be 107.8±1.7±2.5 and 107.0±1.4±2.5MeV/c2, respectively. © 1999 The American Physical Society.