Improved measurements of the neutral current from hadron and lepton production at LEP

We present an update with increased statistics to our published analysis of hadronic and leptonic cross sections and of the leptonic forward-backward asymmetries ine+e − collisions. The published results were based on a total 454 000 hadronic and 58 000 leptonic events. This analysis adds 733 000 hadronic and 88 000 leptonic events recorded at theZ0 peak in 1992 by the OPAL experiment at LEP. A model independent analysis ofZ0 parameters based on an extension of the improved Born approximation leads to tests of lepton universality and gives an interpretation of the results within the Standard Model framework. We also present a model independent test for new physics.