Related papers: Recent LEP 2 Results from OPAL
In five years of operation (1996-2000) the four LEP2 experiments collected roughly 3 fb-1 of data from e+e- collisions at centre-of-mass energies between 161 and 207 GeV, yielding a total of about 40000 W-pair events. The analysis of the…
Knowledge of the beam energy at LEP2 is of primary importance to set the absolute energy scale for the measurement of the W-boson mass. The beam energy above 80 GeV is derived from continuous measurements of the magnetic bending field by 16…
In 1998, the four experiments of LEP, i.e. ALEPH, DELPHI, L3 and OPAL, collected data of about 175 /pb per experiment at the center-of-mass energy of 189 GeV. Using these data, the mass of W boson was directly measured by reconstructing the…
Knowledge of the centre-of-mass energy at LEP2 is of primary importance to set the absolute energy scale for the measurement of the W-boson mass. The beam energy above 80 GeV is derived from continuous measurements of the magnetic bending…
Radiative returns to the Z resonance (Zgamma events) are used to determine the LEP2 centre-of-mass energy from the data collected with the ALEPH detector in 1997. The average centre-of-mass energy is measured to be: E_CM = 182.50 +-…
During the year 2000, LEP has been operated at centre-of-mass energies up to sqrt(s) = 209 GeV. New particle searches have been performed using these data samples. Model independent limits on the production cross-sections and mass limits in…
Since 1995, LEP has steadily increased the center of mass energy of the colliding beams, from the M_Z resonance to 133, 161 and 172 GeV. New measurements of the strong coupling constant, alpha_s, at these energies have been performed by the…
From 1996 up to 2000 the LEP collider at CERN has operated at center of mass energies above the production threshold for W boson pairs of approximately 160 GeV. The obtained data are used to extract a preliminary W mass value of (80.450 +-…
The analyses and results on WW physics obtained in the first year of running of LEP2 are summarized. The determination of the W mass, both through the measurement of the WW production cross section at a center-of-mass energy of 161 GeV and…
The main physics topics of interest at LEP2, the CERN electron-positron collider with center-of-mass energy in the range (161-192) GeV, are reviewed. Progresses in both the precision tests of the standard model and the field of discovery…
We present a determination of the LEP beam energy using "radiative return" fermion-pair events recorded at centre-of-mass energies from 183 GeV to 209 GeV. We find no evidence of a disagreement between the OPAL data and the LEP Energy…
In 1997 each LEP experiment collected approximately $55 {pb}^{-1}$ of data at a center-of-mass energy of 183 GeV. These data yield a sample of candidate $e^+e^- \to W^+W^-$ events from which the mass of the W boson, M_W, is measured. The…
The latest results of Higgs boson searches from the four LEP experiments, ALEPH, DELPHI, L3 and OPAL, are reviewed using the data taken in 1996 at center-of-mass energies between 161 and 172 GeV. No signal was observed. The 95% CL combined…
A search for the Standard Model Higgs boson with the OPAL detector at LEP was reported. The analysis was based on the full data sample collected at center-of-mass energies of 192-209 GeV in 1999 and 2000, corresponding to an integrated…
The energy upgrade at LEP allows new regimes to be explored in the search for physics beyond the Standard Model. The searches for new physics using the ALEPH, DELPHI, L3, and OPAL data are described, and the results are presented.
We review here the measurements of W-pair production and W decay rates performed by the four LEP experiments at ECM from 161 to 209 GeV, and their relevance in support of the standard electroweak model.
Recent tests of the electroweak Standard Model are reviewed, covering the precise measurements of Z decays at LEP I and SLC and measurements of fermion pair production at higher energies at LEP II. Special emphasis is given to new results…
A selection of recent results on searches for phenomena beyond the Standard Model is presented from the LEP Collaborations, based on the data collected up to the highest centre-of-mass energies of 209 GeV.
Cross-sections for hadronic, b-bbar and lepton pair final states in e+e- collisions at sqrt(s) = 183 GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. Forward-backward…
Cross-section and angular distributions for hadronic and lepton-pair final states in e+e- collisions at centre-of-mass energies between 189 GeV and 209 GeV, measured with the OPAL detector at LEP, are presented and compared with the…