A. Chen

The CLEO detector

Abstract The construction and performance of a large aperture magnetic detector designed for use at the Cornell Electon Storage Ring is descr bed.

A measurement of the tau lifetime

The tau lepton lifetime is measured using four different methods with the DELPHI detector. Three measurements using one prong decays are combined, accounting for correlations, resulting in ττ=298 ±7 (stat.)±4 (syst.) fs while the decay length distribution of three prong decays gives ππ=298±13 (stat)±(syst.) fs. The combined result is ττ=298±7 fs. The ratio of the Fermi coupling constant from tau decay relative to that from muon decay is found to be 0.985±0.013, compatible with lepton universality.

Study of the decay BX

We have measured the inclusive branching ratio for B..-->..psiX to be (1.09 +- 0.16 +- 0.21)%, and the exclusive branching ratios for B/sup -/..-->..psiK/sup -/ and B-bar /sup 0/..-->..psiK-bar /sup *//sup 0/ to be (0.09 +- 0.05)% and (0.41 +- 0.18)%, respectively. The mass difference between neutral and charged B mesons is 1.1 +- 2.1 MeV, while the difference between the mass of UPSILON(4S) and twice the mean B-meson mass is 18.5 +- 3.0 MeV. The psi momentum distribution implies a substantial two-body decay (in agreement with direct measurements), but also some combination of B..-->..psiX with M/sub X/>1.5 GeV, and B..-->..psiX.

Measurement of the branching ratio of (3S)+-(1S)

The branching ratio of UPSILON(3S)..--> pi../sup +/..pi../sup -/UPSILON(1S) has been measured to be (4.9 +- 0.9 +- 0.5)%. The di-pion invariant-mass distribution for this decay is flatter than that for the decays UPSILON(2S)..--> pi../sup +/..pi../sup -/UPSILON(1S) and psi..--> pi../sup +/..pi../sup -/psi.

Ruling out exotic models of b quark decay

Abstract We consider three broad classes of nonstandard models for b quark decay: (1) b → llq with charged or neutral leptons of arbitrary flavor; (2) b → l q q ; and (3) b → qa − where a − is a Higgs boson or hyperpion. For these classes of models we have calculated the charged energy fraction and the inclusive yields of electrons, muons, protons, and lambdas. We demonstrate that these model predictions are inconsistent with CLEO measurements at the γ (4S).

Measurement of the D0, D+ and Ds+ meson lifetimes at √s = 10.58 GeV

Abstract We have measured the lifetimes of the D0, D+ and Ds+ mesons with data from the CLEO detector. We find τD0 = (5.0 ± 0.7 ± 0.4) × 10−13s, τD+ = (11.4 ± 1.6 ± 0.7) × 10−13s and τDs+ = (4.7 ± 2.2 ± 0.5) × 10−13s, giving lifetime ratios τD+/τD0 = 2.3 ± 0.5 and τDs+/τD0 = 0.9 ± 0.5.

A search for the ρ(2.2) in the ϒ region

Abstract We have searched in the decays of the ϒ(1S), ϒ(2S) and B mesons for the narrow state, γ, seen by the Mark II group in radiative ψ decay. We find the product branching fractions B[ϒ(1S) → γγ]·B[γ → K+K−], B[ϒ(2S) → γ γ]· B[γ → K+K−] and B[B → γX]·B[γ → K+K−] to be less than 2×10−4, 9×10−5 and 3×10−3, respectively at 90% confidence level. These limits constrain theoretical models if the γ is interpreted as a Higgs boson.

Observation of the decay BFX

We present evidence for inclusive F-italic-meson production in B-italic-meson decay. The product branching fraction B-italic(B-italic..-->..F-italicX-italic)B-italic(F-italic/sup +/..-->..phi..pi../sup +/) is measured to be 0.0038 +- 0.010. The F-italic momentum spectrum indicates the presence of a large component of two-body final states in the decay B-italic..-->..F-italicX-italic.