A. Bean

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 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.

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.