Electroweak parameters of the z0 resonance and the standard model

Contains fulltext : 124399.pdf (publisher's version ) (Open Access

A Measurement of strange baryon production in hadronic Z0 decays

Contains fulltext : 124392.pdf (publisher's version ) (Open Access

Measurement of the B(s)0 lifetime

Contains fulltext : 124376.pdf (publisher's version ) (Open Access

Measurement of gamma (Z0 ---> b anti-b) / gamma (z0 ---> hadrons) using leptons

Contains fulltext : 124374.pdf (publisher's version ) (Open Access

A Determination of alpha-s (M (Z0)) at LEP using resummed QCD calculations

Contains fulltext : 124369.pdf (publisher's version ) (Open Access

The Forward - backward asymmetry of e+ e- ---> b anti-b and e+ e- ---> c anti-c using leptons in hadronic Z0 decays

Contains fulltext : 124386.pdf (preprint version ) (Open Access

A Measurement of K*+- (892) production in hadronic Z0 decays

This is the post-print version of the Article - Copyright @ 1993 Elsevier.Measurements are presented of the inclusive cross section for K∗(892)± production in hadronic decays of the Z0 using a sample of about half a million events recorded with the OPAL experiment at LEP. Charged K∗ mesons are reconstructed in the decay channel K0Sπ±. A mean rate of 0.72±0.02±0.08 K∗ mesons per hadronic event is found. Comparison of the results with predictions of the JETSET and HERWIG models shows that JETSET overestimates the K∗± production cross section while HERWIG is consistent with the data.This study was supported by the Department of Energy, USA, National Science Foundation, USA, Science and Engineering Research Council, UK, Natural Sciences and Engineering Research Council, Canada, Israeli Ministry of Science, Minerva Gesellschaft, Japanese Ministry of Education, Science and Culture (the Monbusho) and a grant under the Monbusho International Science Research Program, American Israeli Bi-national Science Foundation, Direction des Sciences de la Matibre du Commissariat ~ l'Energie Atomique, France, Bundesministerium f'fir Forschung und Technologie, FRG, National Research Council of Canada, Canada, A.P. Sloan Foundation and Junta Nacional de Investigag~o Ciendfica e Tecnolrgica, Portugal

Precision Electroweak Measurements on the Z resonance.

We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron–positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward–backward asymmetries and polarised asymmetries. The mass and width of the Z boson, mZ and ΓZ, and its couplings to fermions, for example the ρ parameter and the effective electroweak mixing angle for leptons, are precisely measured: The number of light neutrino species is determined to be 2.9840±0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward–backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, , and the mass of the W boson, . These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of mt and mW, the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than at 95% confidence level