The mass of the W boson is determined from the direct reconstruction of W decays in WW→qq̄qq̄ and WW→ℓνqq̄ events in e+e- collisions at LEP. The data sample corresponds to an integrated luminosity of ...683 pb-1 collected with the ALEPH detector at centre-of-mass energies up to 209 GeV. To minimise any effect from colour reconnection a new procedure is adopted in which low energy particles are not considered in the mass determination from the qq̄qq̄ channel. The combined result from all channels is \(m_{\text{W}}=80.440 \pm0.043{\text{(stat.)}} \pm0.024{\text{(syst.)}} \pm0.009{\text{(FSI)}} \pm0.009{\text{(LEP)}} \text{GeV/}c^2, \)where FSI represents the possible effects of final state interactions in the qq̄qq̄ channel and LEP indicates the uncertainty in the beam energy. From two-parameter fits to the W mass and width, the W width is found to be \(\Gamma_{\text{W}} = 2.14 \pm0.09{\text{(stat.)}} \pm0.04{\text{(syst.)}} \pm0.05{\text{(FSI)}} \pm0.01{\text{(LEP)}} \text{GeV}. \)
Cross sections, angular distributions and forward-backward asymmetries are presented, of two-fermion events produced in e+e- collisions at centre-of-mass energies from 189 to 209 GeV at LEP, measured ...with the ALEPH detector. Results for e+e-, μ+μ-, τ+τ-, qq̄, bb̄ and cc̄ production are in agreement with the standard model predictions. Constraints are set on scenarios of new physics such as four-fermion contact interactions, leptoquarks, Z′ bosons, TeV-scale quantum gravity and R-parity violating squarks and sneutrinos.
The oscillation phenomenon in the neutral B mesons systems is now well established. The motivations and principles of the measurements are given; then the most recent results from the LEP ...experiments, the CDF collaboration at Fermilab and the SLD collaboration at SLAC are reviewed. The present world average of the B
o
d meson oscillation frequency is Δ
m
d
= 0.471 ± 0.016ps
−1 and the lower limit on the B
o
S oscillation frequency is Δ
m
s
> 12.4 ps
−1 at 95% CL.
The results of searches for selectrons, charginos and neutralinos performed with the data collected by the ALEPH detector at LEP at centre-of-mass energies up to 209 GeV are interpreted in the ...framework of the Minimal Supersymmetric extension of the Standard Model with R-parity conservation. Under the assumptions of gaugino and sfermion mass unification and no sfermion mixing, an absolute lower limit of 73 GeV/c2 is set on the mass of the lighter selectron ẽR at the 95% confidence level. Similarly, limits on the masses of the heavier selectron ẽL and of the sneutrino ν̃e are set at 107 and 84 GeV/c2, respectively. Additional constraints are derived from the results of the searches for Higgs bosons. The results are also interpreted in the framework of minimal supergravity.
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